diff --git a/cirq-core/cirq/transformers/optimize_for_target_gateset.py b/cirq-core/cirq/transformers/optimize_for_target_gateset.py
index d90b35e6ba5..62fbf537720 100644
--- a/cirq-core/cirq/transformers/optimize_for_target_gateset.py
+++ b/cirq-core/cirq/transformers/optimize_for_target_gateset.py
@@ -103,7 +103,6 @@ def optimize_for_target_gateset(
     gateset: Optional['cirq.CompilationTargetGateset'] = None,
     ignore_failures: bool = True,
     max_num_passes: Union[int, None] = 1,
-    preserve_moment_structure: bool = True,
 ) -> 'cirq.Circuit':
     """Transforms the given circuit into an equivalent circuit using gates accepted by `gateset`.
 
@@ -126,7 +125,6 @@ def optimize_for_target_gateset(
             conversion failures raise a ValueError.
         max_num_passes: The maximum number of passes to do. A value of `None` means to keep
             iterating until no further improvements can be made.
-        preserve_moment_structure: Whether to preserve moment structure or not.
     Returns:
         An equivalent circuit containing gates accepted by `gateset`.
 
@@ -160,11 +158,6 @@ def _outerloop():
         for transformer in gateset.postprocess_transformers:
             circuit = transformer(circuit, context=context)
 
-        if not preserve_moment_structure:
-            circuit = circuits.Circuit(
-                op for op in circuit.all_operations()
-            )  # Contract the moments.
-
         num_moments, num_ops = len(circuit), len(tuple(circuit.all_operations()))
         if (num_moments, num_ops) == (initial_num_moments, initial_num_ops):
             # Stop early. No further optimizations can be done.
diff --git a/cirq-core/cirq/transformers/optimize_for_target_gateset_test.py b/cirq-core/cirq/transformers/optimize_for_target_gateset_test.py
index db2bb1a28ad..9753c62553b 100644
--- a/cirq-core/cirq/transformers/optimize_for_target_gateset_test.py
+++ b/cirq-core/cirq/transformers/optimize_for_target_gateset_test.py
@@ -284,37 +284,43 @@ def test_optimize_for_target_gateset_multiple_passes(max_num_passes: Union[int,
         ]
     )
 
-    desired_circuit = cirq.Circuit(
-        cirq.PhasedXZGate(axis_phase_exponent=0.5, x_exponent=-0.5, z_exponent=1.0).on(
-            cirq.LineQubit(4)
-        ),
-        cirq.PhasedXZGate(axis_phase_exponent=-1.0, x_exponent=1, z_exponent=0).on(
-            cirq.LineQubit(1)
+    desired_circuit = cirq.Circuit.from_moments(
+        cirq.Moment(
+            cirq.PhasedXZGate(axis_phase_exponent=0.5, x_exponent=-0.5, z_exponent=1.0).on(
+                cirq.LineQubit(4)
+            )
         ),
-        cirq.PhasedXZGate(axis_phase_exponent=-0.5, x_exponent=0.5, z_exponent=0.0).on(
-            cirq.LineQubit(2)
+        cirq.Moment(cirq.CZ(cirq.LineQubit(4), cirq.LineQubit(5))),
+        cirq.Moment(
+            cirq.PhasedXZGate(axis_phase_exponent=-1.0, x_exponent=1, z_exponent=0).on(
+                cirq.LineQubit(1)
+            ),
+            cirq.PhasedXZGate(axis_phase_exponent=0.5, x_exponent=-0.5, z_exponent=1.0).on(
+                cirq.LineQubit(0)
+            ),
+            cirq.PhasedXZGate(axis_phase_exponent=-1.0, x_exponent=1, z_exponent=0).on(
+                cirq.LineQubit(3)
+            ),
+            cirq.PhasedXZGate(axis_phase_exponent=-0.5, x_exponent=0.5, z_exponent=0.0).on(
+                cirq.LineQubit(2)
+            ),
         ),
-        cirq.PhasedXZGate(axis_phase_exponent=0.5, x_exponent=-0.5, z_exponent=1.0).on(
-            cirq.LineQubit(0)
+        cirq.Moment(
+            cirq.CZ(cirq.LineQubit(0), cirq.LineQubit(1)),
+            cirq.CZ(cirq.LineQubit(2), cirq.LineQubit(3)),
         ),
-        cirq.PhasedXZGate(axis_phase_exponent=-1.0, x_exponent=1, z_exponent=0).on(
-            cirq.LineQubit(3)
+        cirq.Moment(
+            cirq.CZ(cirq.LineQubit(2), cirq.LineQubit(1)),
+            cirq.CZ(cirq.LineQubit(4), cirq.LineQubit(3)),
         ),
-        cirq.PhasedXZGate(axis_phase_exponent=-0.5, x_exponent=0.5, z_exponent=0.0).on(
-            cirq.LineQubit(6)
+        cirq.Moment(
+            cirq.PhasedXZGate(axis_phase_exponent=-0.5, x_exponent=0.5, z_exponent=0.0).on(
+                cirq.LineQubit(6)
+            )
         ),
-        cirq.CZ(cirq.LineQubit(4), cirq.LineQubit(5)),
-        cirq.CZ(cirq.LineQubit(0), cirq.LineQubit(1)),
-        cirq.CZ(cirq.LineQubit(2), cirq.LineQubit(3)),
-        cirq.CZ(cirq.LineQubit(2), cirq.LineQubit(1)),
-        cirq.CZ(cirq.LineQubit(4), cirq.LineQubit(3)),
-        cirq.CZ(cirq.LineQubit(6), cirq.LineQubit(5)),
+        cirq.Moment(cirq.CZ(cirq.LineQubit(6), cirq.LineQubit(5))),
     )
-
     got = cirq.optimize_for_target_gateset(
-        input_circuit,
-        gateset=gateset,
-        max_num_passes=max_num_passes,
-        preserve_moment_structure=False,
+        input_circuit, gateset=gateset, max_num_passes=max_num_passes
     )
     assert got == desired_circuit