diff --git a/src/main/java/io/github/hectorvent/floci/services/rds/RdsQueryHandler.java b/src/main/java/io/github/hectorvent/floci/services/rds/RdsQueryHandler.java
index aff7318ee..c426e5194 100644
--- a/src/main/java/io/github/hectorvent/floci/services/rds/RdsQueryHandler.java
+++ b/src/main/java/io/github/hectorvent/floci/services/rds/RdsQueryHandler.java
@@ -6,6 +6,7 @@
 import io.github.hectorvent.floci.core.common.AwsQueryResponse;
 import io.github.hectorvent.floci.core.common.XmlBuilder;
 import io.github.hectorvent.floci.services.rds.model.DbCluster;
+import io.github.hectorvent.floci.services.rds.model.DbClusterParameterGroup;
 import io.github.hectorvent.floci.services.rds.model.DbEndpoint;
 import io.github.hectorvent.floci.services.rds.model.DbInstance;
 import io.github.hectorvent.floci.services.rds.model.DbInstanceStatus;
@@ -55,6 +56,11 @@ public Response handle(String action, MultivaluedMap<String, String> params) {
                 case "DeleteDBParameterGroup" -> handleDeleteDbParameterGroup(params);
                 case "ModifyDBParameterGroup" -> handleModifyDbParameterGroup(params);
                 case "DescribeDBParameters" -> handleDescribeDbParameters(params);
+                case "CreateDBClusterParameterGroup" -> handleCreateDbClusterParameterGroup(params);
+                case "DescribeDBClusterParameterGroups" -> handleDescribeDbClusterParameterGroups(params);
+                case "DeleteDBClusterParameterGroup" -> handleDeleteDbClusterParameterGroup(params);
+                case "ModifyDBClusterParameterGroup" -> handleModifyDbClusterParameterGroup(params);
+                case "DescribeDBClusterParameters" -> handleDescribeDbClusterParameters(params);
                 default -> AwsQueryResponse.error("UnsupportedOperation",
                         "Operation " + action + " is not supported.", AwsNamespaces.RDS, 400);
             };
@@ -344,6 +350,101 @@ private Response handleDescribeDbParameters(MultivaluedMap<String, String> param
         }
     }
 
+    // ── Cluster Parameter Groups ──────────────────────────────────────────────
+
+    private Response handleCreateDbClusterParameterGroup(MultivaluedMap<String, String> params) {
+        String name = params.getFirst("DBClusterParameterGroupName");
+        String family = params.getFirst("DBParameterGroupFamily");
+        String description = params.getFirst("Description");
+        if (name == null || name.isBlank()) {
+            return AwsQueryResponse.error("InvalidParameterValue", "DBClusterParameterGroupName is required.", AwsNamespaces.RDS, 400);
+        }
+        try {
+            DbClusterParameterGroup group = service.createDbClusterParameterGroup(name, family, description);
+            String result = clusterParamGroupXml(group);
+            return Response.ok(AwsQueryResponse.envelope("CreateDBClusterParameterGroup", AwsNamespaces.RDS, result)).build();
+        } catch (AwsException e) {
+            return AwsQueryResponse.error(e.getErrorCode(), e.getMessage(), AwsNamespaces.RDS, e.getHttpStatus());
+        }
+    }
+
+    private Response handleDescribeDbClusterParameterGroups(MultivaluedMap<String, String> params) {
+        String filterName = params.getFirst("DBClusterParameterGroupName");
+        try {
+            Collection<DbClusterParameterGroup> result = service.listDbClusterParameterGroups(filterName);
+            XmlBuilder xml = new XmlBuilder().start("DBClusterParameterGroups");
+            for (DbClusterParameterGroup g : result) {
+                xml.start("DBClusterParameterGroup").raw(clusterParamGroupInnerXml(g)).end("DBClusterParameterGroup");
+            }
+            xml.end("DBClusterParameterGroups").start("Marker").end("Marker");
+            return Response.ok(AwsQueryResponse.envelope("DescribeDBClusterParameterGroups", AwsNamespaces.RDS, xml.build())).build();
+        } catch (AwsException e) {
+            return AwsQueryResponse.error(e.getErrorCode(), e.getMessage(), AwsNamespaces.RDS, e.getHttpStatus());
+        }
+    }
+
+    private Response handleDeleteDbClusterParameterGroup(MultivaluedMap<String, String> params) {
+        String name = params.getFirst("DBClusterParameterGroupName");
+        if (name == null || name.isBlank()) {
+            return AwsQueryResponse.error("InvalidParameterValue", "DBClusterParameterGroupName is required.", AwsNamespaces.RDS, 400);
+        }
+        try {
+            service.deleteDbClusterParameterGroup(name);
+            return Response.ok(AwsQueryResponse.envelopeNoResult("DeleteDBClusterParameterGroup", AwsNamespaces.RDS)).build();
+        } catch (AwsException e) {
+            return AwsQueryResponse.error(e.getErrorCode(), e.getMessage(), AwsNamespaces.RDS, e.getHttpStatus());
+        }
+    }
+
+    private Response handleModifyDbClusterParameterGroup(MultivaluedMap<String, String> params) {
+        String name = params.getFirst("DBClusterParameterGroupName");
+        if (name == null || name.isBlank()) {
+            return AwsQueryResponse.error("InvalidParameterValue", "DBClusterParameterGroupName is required.", AwsNamespaces.RDS, 400);
+        }
+        Map<String, String> parameters = new HashMap<>();
+        for (int n = 1; ; n++) {
+            String paramName = params.getFirst("Parameters.member." + n + ".ParameterName");
+            if (paramName == null) {
+                break;
+            }
+            String paramValue = params.getFirst("Parameters.member." + n + ".ParameterValue");
+            if (paramValue != null) {
+                parameters.put(paramName, paramValue);
+            }
+        }
+        try {
+            DbClusterParameterGroup group = service.modifyDbClusterParameterGroup(name, parameters);
+            String result = new XmlBuilder()
+                    .elem("DBClusterParameterGroupName", group.getDbClusterParameterGroupName())
+                    .build();
+            return Response.ok(AwsQueryResponse.envelope("ModifyDBClusterParameterGroup", AwsNamespaces.RDS, result)).build();
+        } catch (AwsException e) {
+            return AwsQueryResponse.error(e.getErrorCode(), e.getMessage(), AwsNamespaces.RDS, e.getHttpStatus());
+        }
+    }
+
+    private Response handleDescribeDbClusterParameters(MultivaluedMap<String, String> params) {
+        String name = params.getFirst("DBClusterParameterGroupName");
+        if (name == null || name.isBlank()) {
+            return AwsQueryResponse.error("InvalidParameterValue", "DBClusterParameterGroupName is required.", AwsNamespaces.RDS, 400);
+        }
+        try {
+            DbClusterParameterGroup group = service.getDbClusterParameterGroup(name);
+            XmlBuilder xml = new XmlBuilder().start("Parameters");
+            for (Map.Entry<String, String> entry : group.getParameters().entrySet()) {
+                xml.start("member")
+                   .elem("ParameterName", entry.getKey())
+                   .elem("ParameterValue", entry.getValue())
+                   .elem("IsModifiable", true)
+                   .end("member");
+            }
+            xml.end("Parameters").start("Marker").end("Marker");
+            return Response.ok(AwsQueryResponse.envelope("DescribeDBClusterParameters", AwsNamespaces.RDS, xml.build())).build();
+        } catch (AwsException e) {
+            return AwsQueryResponse.error(e.getErrorCode(), e.getMessage(), AwsNamespaces.RDS, e.getHttpStatus());
+        }
+    }
+
     // ── XML builders ──────────────────────────────────────────────────────────
 
     private String dbInstanceXml(DbInstance i) {
@@ -472,6 +573,18 @@ private String paramGroupInnerXml(DbParameterGroup g) {
                 .build();
     }
 
+    private String clusterParamGroupXml(DbClusterParameterGroup g) {
+        return new XmlBuilder().start("DBClusterParameterGroup").raw(clusterParamGroupInnerXml(g)).end("DBClusterParameterGroup").build();
+    }
+
+    private String clusterParamGroupInnerXml(DbClusterParameterGroup g) {
+        return new XmlBuilder()
+                .elem("DBClusterParameterGroupName", g.getDbClusterParameterGroupName())
+                .elem("DBParameterGroupFamily", g.getDbParameterGroupFamily())
+                .elem("Description", g.getDescription())
+                .build();
+    }
+
     private String statusLabel(DbInstanceStatus status) {
         return switch (status) {
             case CREATING -> "creating";
diff --git a/src/main/java/io/github/hectorvent/floci/services/rds/RdsService.java b/src/main/java/io/github/hectorvent/floci/services/rds/RdsService.java
index f9ac7e48c..095e26ca8 100644
--- a/src/main/java/io/github/hectorvent/floci/services/rds/RdsService.java
+++ b/src/main/java/io/github/hectorvent/floci/services/rds/RdsService.java
@@ -9,6 +9,7 @@
 import io.github.hectorvent.floci.services.rds.container.RdsContainerManager;
 import io.github.hectorvent.floci.services.rds.model.DatabaseEngine;
 import io.github.hectorvent.floci.services.rds.model.DbCluster;
+import io.github.hectorvent.floci.services.rds.model.DbClusterParameterGroup;
 import io.github.hectorvent.floci.services.rds.model.DbEndpoint;
 import io.github.hectorvent.floci.services.rds.model.DbInstance;
 import io.github.hectorvent.floci.services.rds.model.DbInstanceStatus;
@@ -38,6 +39,7 @@ public class RdsService {
     private final StorageBackend<String, DbInstance> instances;
     private final StorageBackend<String, DbCluster> clusters;
     private final StorageBackend<String, DbParameterGroup> parameterGroups;
+    private final StorageBackend<String, DbClusterParameterGroup> clusterParameterGroups;
     private final RdsContainerManager containerManager;
     private final RdsProxyManager proxyManager;
     private final RegionResolver regionResolver;
@@ -56,6 +58,7 @@ public RdsService(RdsContainerManager containerManager,
         this.instances = new InMemoryStorage<>();
         this.clusters = new InMemoryStorage<>();
         this.parameterGroups = new InMemoryStorage<>();
+        this.clusterParameterGroups = new InMemoryStorage<>();
     }
 
     // ── DB Instances ──────────────────────────────────────────────────────────
@@ -369,6 +372,49 @@ public DbParameterGroup modifyDbParameterGroup(String name,
         return group;
     }
 
+    // ── Cluster Parameter Groups ──────────────────────────────────────────────
+
+    public DbClusterParameterGroup createDbClusterParameterGroup(String name, String family, String description) {
+        if (clusterParameterGroups.get(name).isPresent()) {
+            throw new AwsException("DBParameterGroupAlreadyExists",
+                    "DB cluster parameter group " + name + " already exists.", 400);
+        }
+        DbClusterParameterGroup group = new DbClusterParameterGroup(name, family, description);
+        clusterParameterGroups.put(name, group);
+        return group;
+    }
+
+    public DbClusterParameterGroup getDbClusterParameterGroup(String name) {
+        return clusterParameterGroups.get(name).orElseThrow(() ->
+                new AwsException("DBParameterGroupNotFound",
+                        "DB cluster parameter group " + name + " not found.", 404));
+    }
+
+    public Collection<DbClusterParameterGroup> listDbClusterParameterGroups(String filterName) {
+        if (filterName != null && !filterName.isBlank()) {
+            return clusterParameterGroups.get(filterName).map(List::of).orElse(List.of());
+        }
+        return clusterParameterGroups.scan(k -> true);
+    }
+
+    public void deleteDbClusterParameterGroup(String name) {
+        if (clusterParameterGroups.get(name).isEmpty()) {
+            throw new AwsException("DBParameterGroupNotFound",
+                    "DB cluster parameter group " + name + " not found.", 404);
+        }
+        clusterParameterGroups.delete(name);
+    }
+
+    public DbClusterParameterGroup modifyDbClusterParameterGroup(String name,
+                                                                  java.util.Map<String, String> parameters) {
+        DbClusterParameterGroup group = getDbClusterParameterGroup(name);
+        if (parameters != null) {
+            group.getParameters().putAll(parameters);
+        }
+        clusterParameterGroups.put(name, group);
+        return group;
+    }
+
     // ── Password validation callbacks ─────────────────────────────────────────
 
     public boolean validateDbPassword(String instanceId, String clientUser, String password) {
diff --git a/src/main/java/io/github/hectorvent/floci/services/rds/model/DbClusterParameterGroup.java b/src/main/java/io/github/hectorvent/floci/services/rds/model/DbClusterParameterGroup.java
new file mode 100644
index 000000000..f4b2847f9
--- /dev/null
+++ b/src/main/java/io/github/hectorvent/floci/services/rds/model/DbClusterParameterGroup.java
@@ -0,0 +1,36 @@
+package io.github.hectorvent.floci.services.rds.model;
+
+import io.quarkus.runtime.annotations.RegisterForReflection;
+
+import java.util.HashMap;
+import java.util.Map;
+
+@RegisterForReflection
+public class DbClusterParameterGroup {
+
+    private String dbClusterParameterGroupName;
+    private String dbParameterGroupFamily;
+    private String description;
+    private Map<String, String> parameters = new HashMap<>();
+
+    public DbClusterParameterGroup() {}
+
+    public DbClusterParameterGroup(String dbClusterParameterGroupName, String dbParameterGroupFamily,
+                                   String description) {
+        this.dbClusterParameterGroupName = dbClusterParameterGroupName;
+        this.dbParameterGroupFamily = dbParameterGroupFamily;
+        this.description = description;
+    }
+
+    public String getDbClusterParameterGroupName() { return dbClusterParameterGroupName; }
+    public void setDbClusterParameterGroupName(String dbClusterParameterGroupName) { this.dbClusterParameterGroupName = dbClusterParameterGroupName; }
+
+    public String getDbParameterGroupFamily() { return dbParameterGroupFamily; }
+    public void setDbParameterGroupFamily(String dbParameterGroupFamily) { this.dbParameterGroupFamily = dbParameterGroupFamily; }
+
+    public String getDescription() { return description; }
+    public void setDescription(String description) { this.description = description; }
+
+    public Map<String, String> getParameters() { return parameters; }
+    public void setParameters(Map<String, String> parameters) { this.parameters = parameters; }
+}
diff --git a/src/test/java/io/github/hectorvent/floci/services/rds/RdsQueryHandlerTest.java b/src/test/java/io/github/hectorvent/floci/services/rds/RdsQueryHandlerTest.java
index 9718204cf..bd7e9591b 100644
--- a/src/test/java/io/github/hectorvent/floci/services/rds/RdsQueryHandlerTest.java
+++ b/src/test/java/io/github/hectorvent/floci/services/rds/RdsQueryHandlerTest.java
@@ -3,6 +3,7 @@
 import io.github.hectorvent.floci.config.EmulatorConfig;
 import io.github.hectorvent.floci.core.common.AwsException;
 import io.github.hectorvent.floci.services.rds.model.DbCluster;
+import io.github.hectorvent.floci.services.rds.model.DbClusterParameterGroup;
 import io.github.hectorvent.floci.services.rds.model.DbInstance;
 import io.github.hectorvent.floci.services.rds.model.DbInstanceStatus;
 import io.github.hectorvent.floci.services.rds.model.DbParameterGroup;
@@ -215,6 +216,77 @@ void unsupportedOperationReturnsQueryError() {
         assertTrue(((String) response.getEntity()).contains("UnsupportedOperation"));
     }
 
+    // ──────────────────────────── DBClusterParameterGroups ──────────────────────
+
+    @Test
+    void describeDbClusterParameterGroups_usesDBClusterParameterGroupTag() {
+        DbClusterParameterGroup group = new DbClusterParameterGroup("cpg1", "aurora-postgresql16", "test cluster group");
+        when(service.listDbClusterParameterGroups(null)).thenReturn(List.of(group));
+
+        Response response = handler.handle("DescribeDBClusterParameterGroups", params());
+
+        String body = (String) response.getEntity();
+        assertTrue(body.contains("<DBClusterParameterGroup>"), "Expected <DBClusterParameterGroup> element in response");
+        assertFalse(body.contains("<member><DBClusterParameterGroupName>"), "Did not expect <member> wrapping DBClusterParameterGroup");
+    }
+
+    @Test
+    void createDbClusterParameterGroup_requiresName() {
+        Response response = handler.handle("CreateDBClusterParameterGroup", params());
+
+        assertEquals(400, response.getStatus());
+        assertTrue(((String) response.getEntity()).contains("DBClusterParameterGroupName is required."));
+    }
+
+    @Test
+    void createDbClusterParameterGroup_passesArgumentsToService() {
+        DbClusterParameterGroup group = new DbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc");
+        when(service.createDbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc")).thenReturn(group);
+
+        MultivaluedMap<String, String> p = params();
+        p.add("DBClusterParameterGroupName", "cpg1");
+        p.add("DBParameterGroupFamily", "aurora-postgresql16");
+        p.add("Description", "desc");
+        Response response = handler.handle("CreateDBClusterParameterGroup", p);
+
+        verify(service).createDbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc");
+        String body = (String) response.getEntity();
+        assertTrue(body.contains("<DBClusterParameterGroupName>cpg1</DBClusterParameterGroupName>"));
+        assertTrue(body.contains("<DBParameterGroupFamily>aurora-postgresql16</DBParameterGroupFamily>"));
+    }
+
+    @Test
+    void modifyDbClusterParameterGroup_ignoresParametersWithoutValue() {
+        DbClusterParameterGroup group = new DbClusterParameterGroup("cpg1", "aurora-postgresql16", "test group");
+        when(service.modifyDbClusterParameterGroup(eq("cpg1"), eq(java.util.Map.of("log_statement", "all"))))
+                .thenReturn(group);
+
+        MultivaluedMap<String, String> p = params();
+        p.add("DBClusterParameterGroupName", "cpg1");
+        p.add("Parameters.member.1.ParameterName", "log_statement");
+        p.add("Parameters.member.1.ParameterValue", "all");
+        p.add("Parameters.member.2.ParameterName", "ignored_without_value");
+        handler.handle("ModifyDBClusterParameterGroup", p);
+
+        verify(service).modifyDbClusterParameterGroup("cpg1", java.util.Map.of("log_statement", "all"));
+    }
+
+    @Test
+    void describeDbClusterParameters_requiresParameterGroupName() {
+        Response response = handler.handle("DescribeDBClusterParameters", params());
+
+        assertEquals(400, response.getStatus());
+        assertTrue(((String) response.getEntity()).contains("DBClusterParameterGroupName is required."));
+    }
+
+    @Test
+    void deleteDbClusterParameterGroup_requiresName() {
+        Response response = handler.handle("DeleteDBClusterParameterGroup", params());
+
+        assertEquals(400, response.getStatus());
+        assertTrue(((String) response.getEntity()).contains("DBClusterParameterGroupName is required."));
+    }
+
     // ──────────────────────────── DBSubnetGroup shape ───────────────────────────
 
     @Test
diff --git a/src/test/java/io/github/hectorvent/floci/services/rds/RdsServiceTest.java b/src/test/java/io/github/hectorvent/floci/services/rds/RdsServiceTest.java
index c81ba3d5d..5a1eef097 100644
--- a/src/test/java/io/github/hectorvent/floci/services/rds/RdsServiceTest.java
+++ b/src/test/java/io/github/hectorvent/floci/services/rds/RdsServiceTest.java
@@ -5,6 +5,7 @@
 import io.github.hectorvent.floci.core.common.RegionResolver;
 import io.github.hectorvent.floci.services.rds.model.DatabaseEngine;
 import io.github.hectorvent.floci.services.rds.model.DbCluster;
+import io.github.hectorvent.floci.services.rds.model.DbClusterParameterGroup;
 import io.github.hectorvent.floci.services.rds.container.RdsContainerHandle;
 import io.github.hectorvent.floci.services.rds.container.RdsContainerManager;
 import io.github.hectorvent.floci.services.rds.model.DbInstance;
@@ -116,4 +117,56 @@ void deleteDbClusterFailsWhenMembersRemain() {
         assertEquals("InvalidDBClusterStateFault", exception.getErrorCode());
         assertTrue(exception.getMessage().contains("still has DB instances"));
     }
+
+    @Test
+    void createDbClusterParameterGroupRoundTrip() {
+        DbClusterParameterGroup created = rdsService.createDbClusterParameterGroup(
+                "cpg1", "aurora-postgresql16", "test cluster group");
+
+        assertEquals("cpg1", created.getDbClusterParameterGroupName());
+        assertEquals("aurora-postgresql16", created.getDbParameterGroupFamily());
+
+        DbClusterParameterGroup fetched = rdsService.getDbClusterParameterGroup("cpg1");
+        assertEquals("cpg1", fetched.getDbClusterParameterGroupName());
+
+        Collection<DbClusterParameterGroup> listed = rdsService.listDbClusterParameterGroups(null);
+        assertEquals(1, listed.size());
+    }
+
+    @Test
+    void createDbClusterParameterGroupRejectsDuplicate() {
+        rdsService.createDbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc");
+
+        AwsException exception = assertThrows(AwsException.class, () ->
+                rdsService.createDbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc"));
+
+        assertEquals("DBParameterGroupAlreadyExists", exception.getErrorCode());
+    }
+
+    @Test
+    void modifyDbClusterParameterGroupAppliesParameters() {
+        rdsService.createDbClusterParameterGroup("cpg1", "aurora-postgresql16", "desc");
+
+        DbClusterParameterGroup modified = rdsService.modifyDbClusterParameterGroup(
+                "cpg1", java.util.Map.of("log_statement", "all", "shared_preload_libraries", "pg_stat_statements"));
+
+        assertEquals("all", modified.getParameters().get("log_statement"));
+        assertEquals("pg_stat_statements", modified.getParameters().get("shared_preload_libraries"));
+    }
+
+    @Test
+    void deleteDbClusterParameterGroupMissingThrows() {
+        AwsException exception = assertThrows(AwsException.class, () ->
+                rdsService.deleteDbClusterParameterGroup("nonexistent"));
+
+        assertEquals("DBParameterGroupNotFound", exception.getErrorCode());
+    }
+
+    @Test
+    void getDbClusterParameterGroupMissingThrows() {
+        AwsException exception = assertThrows(AwsException.class, () ->
+                rdsService.getDbClusterParameterGroup("nonexistent"));
+
+        assertEquals("DBParameterGroupNotFound", exception.getErrorCode());
+    }
 }