diff --git a/jwst/regtest/test_nirspec_mos_fs_spec2.py b/jwst/regtest/test_nirspec_mos_fs_spec2.py
new file mode 100644
index 00000000000..bcceb0d4f62
--- /dev/null
+++ b/jwst/regtest/test_nirspec_mos_fs_spec2.py
@@ -0,0 +1,55 @@
+import pytest
+
+from astropy.io.fits.diff import FITSDiff
+
+from jwst.stpipe import Step
+
+
+@pytest.fixture(scope="module")
+def run_pipeline(rtdata_module):
+    """Run the calwebb_spec2 pipeline on a single NIRSpec MOS/FS exposure."""
+
+    rtdata = rtdata_module
+
+    # Get the MSA metadata file referenced in the input exposure
+    rtdata.get_data("nirspec/mos/jw02674004001_01_msa.fits")
+
+    # Get the input ASN file and exposures
+    rtdata.get_data("nirspec/mos/jw02674004001_03101_00001_nrs1_rate.fits")
+
+    # Run the calwebb_spec2 pipeline; save results from intermediate steps
+    args = ["calwebb_spec2", rtdata.input,
+            "--steps.assign_wcs.save_results=true",
+            "--steps.msa_flagging.save_results=true",
+            "--steps.master_background_mos.save_results=true",
+            "--steps.extract_2d.save_results=true",
+            "--steps.srctype.save_results=true",
+            "--steps.wavecorr.save_results=true",
+            "--steps.flat_field.save_results=true",
+            "--steps.pathloss.save_results=true",
+            "--steps.barshadow.save_results=true"]
+    Step.from_cmdline(args)
+
+    return rtdata
+
+
+@pytest.mark.bigdata
+@pytest.mark.parametrize("suffix", [
+    "assign_wcs", "msa_flagging", "extract_2d", "srctype",
+    "master_background_mos", "wavecorr", "flat_field", "pathloss", "barshadow",
+    "wavecorr_fs", "flat_field_fs", "pathloss_fs", "barshadow_fs",
+    "cal", "s2d", "x1d"])
+def test_nirspec_mos_fs_spec2(run_pipeline, fitsdiff_default_kwargs, suffix):
+    """Regression test for calwebb_spec2 on a NIRSpec MOS/FS exposure."""
+
+    # Run the pipeline and retrieve outputs
+    rtdata = run_pipeline
+    output = f"jw02674004001_03101_00001_nrs1_{suffix}.fits"
+    rtdata.output = output
+
+    # Get the truth files
+    rtdata.get_truth("truth/test_nirspec_mos_fs_spec2/" + output)
+
+    # Compare the results
+    diff = FITSDiff(rtdata.output, rtdata.truth, **fitsdiff_default_kwargs)
+    assert diff.identical, diff.report()
diff --git a/jwst/regtest/test_nirspec_mos_fs_spec3.py b/jwst/regtest/test_nirspec_mos_fs_spec3.py
new file mode 100644
index 00000000000..dcea1949487
--- /dev/null
+++ b/jwst/regtest/test_nirspec_mos_fs_spec3.py
@@ -0,0 +1,42 @@
+import pytest
+from astropy.io.fits.diff import FITSDiff
+import numpy as np
+from gwcs import wcstools
+
+from jwst.stpipe import Step
+from stdatamodels.jwst import datamodels
+
+
+@pytest.fixture(scope="module")
+def run_pipeline(rtdata_module):
+    """Run calwebb_spec3 on NIRSpec MOS data."""
+    rtdata = rtdata_module
+    rtdata.get_asn("nirspec/mos/jw02674-o004_20240305t054741_spec3_00001_asn.json")
+
+    # Run the calwebb_spec3 pipeline on the association
+    args = ["calwebb_spec3", rtdata.input]
+    Step.from_cmdline(args)
+
+    return rtdata
+
+
+@pytest.mark.bigdata
+@pytest.mark.parametrize("suffix", ["cal", "crf", "s2d", "x1d"])
+@pytest.mark.parametrize("source_id", ["s01354", "s12105", "s34946",
+                                       "s34949", "s34950", "s34951", "s34952",
+                                       "s34953", "s34954", "s34955"])
+def test_nirspec_mos_fs_spec3(run_pipeline, suffix, source_id, fitsdiff_default_kwargs):
+    """Check results of calwebb_spec3"""
+    rtdata = run_pipeline
+
+    output = f"jw02674-o004_{source_id}_nirspec_f290lp-g395m_{suffix}.fits"
+    rtdata.output = output
+    rtdata.get_truth(f"truth/test_nirspec_mos_fs_spec3/{output}")
+
+    # Adjust tolerance for machine precision with float32 drizzle code
+    if suffix == "s2d":
+        fitsdiff_default_kwargs["rtol"] = 1e-4
+        fitsdiff_default_kwargs["atol"] = 1e-5
+
+    diff = FITSDiff(rtdata.output, rtdata.truth, **fitsdiff_default_kwargs)
+    assert diff.identical, diff.report()