diff --git a/CHANGELOG.md b/CHANGELOG.md
index 334eadf..b6f9cba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,17 @@ All notable changes to the Agent365 TypeScript SDK will be documented in this fi
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+- Support for `A365_OBSERVABILITY_SCOPE_OVERRIDE` (singular) environment variable for cross-SDK compatibility with .NET SDK (PR #133 parity).
+  - The singular form takes precedence when both singular and plural forms are set
+  - Maintains backward compatibility with existing `A365_OBSERVABILITY_SCOPES_OVERRIDE` (plural) that supports multiple whitespace-separated scopes
+  - Updated documentation in `.env.example` files
+
+### Notes
+- This change maintains full backward compatibility. Existing code using `A365_OBSERVABILITY_SCOPES_OVERRIDE` continues to work without any changes.
+
 ## [1.1.0] - 2025-12-09
 
 ### Changed
diff --git a/packages/agents-a365-runtime/src/environment-utils.ts b/packages/agents-a365-runtime/src/environment-utils.ts
index 25e4a6f..e4fd7bf 100644
--- a/packages/agents-a365-runtime/src/environment-utils.ts
+++ b/packages/agents-a365-runtime/src/environment-utils.ts
@@ -18,19 +18,31 @@ export const DEVELOPMENT_ENVIRONMENT_NAME = 'Development';
  * Returns the scope for authenticating to the observability service
  *
  * The default is the production observability scope, but this can be overridden
- * for internal development and testing scenarios using the
- * `A365_OBSERVABILITY_SCOPES_OVERRIDE` environment variable.
+ * for internal development and testing scenarios using either the
+ * `A365_OBSERVABILITY_SCOPE_OVERRIDE` (singular, for a single scope) or
+ * `A365_OBSERVABILITY_SCOPES_OVERRIDE` (plural, supports multiple whitespace-separated scopes)
+ * environment variable.
  *
- * When the override is set to a non-empty string, it is split on whitespace
- * into individual scopes.
+ * The singular form takes precedence and returns a single scope without splitting.
+ * The plural form splits on whitespace to support multiple scopes.
+ * This dual support provides cross-SDK compatibility with the .NET SDK while maintaining
+ * enhanced functionality.
  *
  * @returns The authentication scopes for the current environment.
  */
 export function getObservabilityAuthenticationScope(): string[] {
-  const override = process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE;
+  // Check singular form first for .NET SDK compatibility (PR #133)
+  // Returns a single scope without splitting on whitespace
+  const singularOverride = process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE;
+  if (singularOverride && singularOverride.trim().length > 0) {
+    return [singularOverride.trim()];
+  }
 
-  if (override && override.trim().length > 0) {
-    return override.trim().split(/\s+/);
+  // Check plural form (original TypeScript implementation)
+  // Supports multiple whitespace-separated scopes
+  const pluralOverride = process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE;
+  if (pluralOverride && pluralOverride.trim().length > 0) {
+    return pluralOverride.trim().split(/\s+/);
   }
 
   return [PROD_OBSERVABILITY_SCOPE];
diff --git a/tests-agent/basic-agent-sdk-sample/.env.example b/tests-agent/basic-agent-sdk-sample/.env.example
index ca45fbd..4c9fce9 100644
--- a/tests-agent/basic-agent-sdk-sample/.env.example
+++ b/tests-agent/basic-agent-sdk-sample/.env.example
@@ -16,4 +16,5 @@ CLUSTER_CATEGORY=prod # optional - defaults to 'prod' if not set
 A365_OBSERVABILITY_LOG_LEVEL= # optional - set to enable observability logs, value can be 'info', 'warn', or 'error', default to 'none' if not set
 Use_Custom_Resolver= # optional - set to 'true' to use custom token resolver, defaults to 'false' if not set
 A365_OBSERVABILITY_DOMAIN_OVERRIDE= # optional - set to override the default observability domain
-A365_OBSERVABILITY_SCOPES_OVERRIDE= # optional - set to override the default observability scopes
+A365_OBSERVABILITY_SCOPE_OVERRIDE= # optional - set to override the default observability scope (singular, for single scope, cross-SDK compatible)
+A365_OBSERVABILITY_SCOPES_OVERRIDE= # optional - set to override the default observability scopes (plural, supports multiple whitespace-separated scopes)
diff --git a/tests/runtime/environment-utils.test.ts b/tests/runtime/environment-utils.test.ts
index 512b22c..82c8b04 100644
--- a/tests/runtime/environment-utils.test.ts
+++ b/tests/runtime/environment-utils.test.ts
@@ -25,6 +25,7 @@ describe('environment-utils', () => {
   describe('getObservabilityAuthenticationScope', () => {
     it('should return production observability scope when override is not set', () => {
       delete process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE;
+      delete process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE;
 
       const scopes = getObservabilityAuthenticationScope();
 
@@ -33,6 +34,7 @@ describe('environment-utils', () => {
     });
 
     it('should return overridden observability scope when A365_OBSERVABILITY_SCOPES_OVERRIDE is set', () => {
+      delete process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE;
       process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE = 'https://override.example.com/.default';
 
       const scopes = getObservabilityAuthenticationScope();
@@ -41,6 +43,7 @@ describe('environment-utils', () => {
     });
 
     it('should support multiple scopes separated by whitespace', () => {
+      delete process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE;
       process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE = 'scope-one/.default scope-two/.default';
 
       const scopes = getObservabilityAuthenticationScope();
@@ -49,12 +52,40 @@ describe('environment-utils', () => {
     });
 
     it('should fall back to production scope when override is empty or whitespace', () => {
+      delete process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE;
       process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE = '   ';
 
       const scopes = getObservabilityAuthenticationScope();
 
       expect(scopes).toEqual([PROD_OBSERVABILITY_SCOPE]);
     });
+
+    it('should return overridden observability scope when A365_OBSERVABILITY_SCOPE_OVERRIDE is set (singular form for .NET SDK compatibility)', () => {
+      delete process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE;
+      process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE = 'https://override.singular.com/.default';
+
+      const scopes = getObservabilityAuthenticationScope();
+
+      expect(scopes).toEqual(['https://override.singular.com/.default']);
+    });
+
+    it('should prioritize A365_OBSERVABILITY_SCOPE_OVERRIDE (singular) over A365_OBSERVABILITY_SCOPES_OVERRIDE (plural) when both are set', () => {
+      process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE = 'https://singular.example.com/.default';
+      process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE = 'https://plural.example.com/.default';
+
+      const scopes = getObservabilityAuthenticationScope();
+
+      expect(scopes).toEqual(['https://singular.example.com/.default']);
+    });
+
+    it('should fall back to production scope when singular override is empty or whitespace', () => {
+      delete process.env.A365_OBSERVABILITY_SCOPES_OVERRIDE;
+      process.env.A365_OBSERVABILITY_SCOPE_OVERRIDE = '   ';
+
+      const scopes = getObservabilityAuthenticationScope();
+
+      expect(scopes).toEqual([PROD_OBSERVABILITY_SCOPE]);
+    });
   });
 
   describe('getClusterCategory', () => {