diff --git a/jwst/regtest/test_miri_image.py b/jwst/regtest/test_miri_image.py
index 2d6f46061f..b6863eccec 100644
--- a/jwst/regtest/test_miri_image.py
+++ b/jwst/regtest/test_miri_image.py
@@ -32,6 +32,52 @@ def run_detector1(rtdata_module):
     Step.from_cmdline(args)
 
 
+@pytest.fixture(scope="module")
+def run_detector1_multiprocess_rate(rtdata_module):
+    """Run detector1 pipeline on MIRI imaging data."""
+    rtdata = rtdata_module
+    rtdata.get_data("miri/image/jw01024001001_04101_00001_mirimage_uncal.fits")
+
+    # Run detector1 pipeline only on one of the _uncal files
+    args = ["jwst.pipeline.Detector1Pipeline", rtdata.input,
+            "--save_calibrated_ramp=True",
+            "--steps.dq_init.save_results=True",
+            "--steps.saturation.save_results=True",
+            "--steps.firstframe.save_results=True",
+            "--steps.lastframe.save_results=True",
+            "--steps.reset.save_results=True",
+            "--steps.linearity.save_results=True",
+            "--steps.rscd.save_results=True",
+            "--steps.dark_current.save_results=True",
+            "--steps.refpix.save_results=True",
+            "--steps.ramp_fit.maximum_cores=2", # Multiprocessing
+            ]
+    Step.from_cmdline(args)
+
+
+@pytest.fixture(scope="module")
+def run_detector1_multiprocess_jump(rtdata_module):
+    """Run detector1 pipeline on MIRI imaging data."""
+    rtdata = rtdata_module
+    rtdata.get_data("miri/image/jw01024001001_04101_00001_mirimage_uncal.fits")
+
+    # Run detector1 pipeline only on one of the _uncal files
+    args = ["jwst.pipeline.Detector1Pipeline", rtdata.input,
+            "--save_calibrated_ramp=True",
+            "--steps.dq_init.save_results=True",
+            "--steps.saturation.save_results=True",
+            "--steps.firstframe.save_results=True",
+            "--steps.lastframe.save_results=True",
+            "--steps.reset.save_results=True",
+            "--steps.linearity.save_results=True",
+            "--steps.rscd.save_results=True",
+            "--steps.dark_current.save_results=True",
+            "--steps.refpix.save_results=True",
+            "--steps.jump.maximum_cores=2", # Multiprocessing
+            ]
+    Step.from_cmdline(args)
+
+
 @pytest.fixture(scope="module")
 def run_detector1_with_average_dark_current(rtdata_module):
     """Run detector1 pipeline on MIRI imaging data, providing an
@@ -115,6 +161,18 @@ def test_miri_image_detector1(run_detector1, rtdata_module, fitsdiff_default_kwa
     _assert_is_same(rtdata_module, fitsdiff_default_kwargs, suffix)
 
 
+@pytest.mark.bigdata
+def test_miri_image_detector1_multiprocess_rate(run_detector1_multiprocess_rate, rtdata_module, fitsdiff_default_kwargs):
+    """Regression test of detector1 pipeline performed on MIRI imaging data."""
+    _assert_is_same(rtdata_module, fitsdiff_default_kwargs, "rate")
+
+
+@pytest.mark.bigdata
+def test_miri_image_detector1_multiprocess_jump(run_detector1_multiprocess_jump, rtdata_module, fitsdiff_default_kwargs):
+    """Regression test of detector1 pipeline performed on MIRI imaging data."""
+    _assert_is_same(rtdata_module, fitsdiff_default_kwargs, "rate")
+
+
 @pytest.mark.bigdata
 def test_detector1_mem_usage(rtdata_module):
     """Determine the memory usage for Detector 1"""
diff --git a/jwst/regtest/test_niriss_image.py b/jwst/regtest/test_niriss_image.py
index cf07ae16df..be31fbda67 100644
--- a/jwst/regtest/test_niriss_image.py
+++ b/jwst/regtest/test_niriss_image.py
@@ -36,6 +36,84 @@ def run_detector1(rtdata_module):
     Step.from_cmdline(args)
 
 
+@pytest.fixture(scope="module")
+def run_detector1_multiprocess_rate(rtdata_module):
+    """Run calwebb_detector1 pipeline on NIRISS imaging data."""
+    rtdata = rtdata_module
+
+    rtdata.get_data("niriss/imaging/jw01094001002_02107_00001_nis_uncal.fits")
+
+    # Run detector1 pipeline on an _uncal files
+    args = ["calwebb_detector1", rtdata.input,
+            "--steps.persistence.save_trapsfilled=False",
+            "--steps.dq_init.save_results=True",
+            "--steps.saturation.save_results=True",
+            "--steps.superbias.save_results=True",
+            "--steps.refpix.save_results=True",
+            "--steps.linearity.save_results=True",
+            "--steps.dark_current.save_results=True",
+            "--steps.charge_migration.skip=False",
+            "--steps.charge_migration.save_results=True",
+            "--steps.jump.save_results=True",
+            "--steps.ramp_fit.maximum_cores=2", # Multiprocessing
+            ]
+
+    Step.from_cmdline(args)
+
+
+@pytest.fixture(scope="module")
+def run_detector1_multiprocess_rate_save_opt(rtdata_module):
+    """Run calwebb_detector1 pipeline on NIRISS imaging data."""
+    rtdata = rtdata_module
+
+    rtdata.get_data("niriss/imaging/jw01094001002_02107_00001_nis_uncal.fits")
+
+    # Run detector1 pipeline on an _uncal files
+    args = ["calwebb_detector1", rtdata.input,
+            "--steps.persistence.save_trapsfilled=False",
+            "--steps.dq_init.save_results=True",
+            "--steps.saturation.save_results=True",
+            "--steps.superbias.save_results=True",
+            "--steps.refpix.save_results=True",
+            "--steps.linearity.save_results=True",
+            "--steps.dark_current.save_results=True",
+            "--steps.charge_migration.skip=False",
+            "--steps.charge_migration.save_results=True",
+            "--steps.jump.save_results=True",
+            "--steps.ramp_fit.maximum_cores=2", # Multiprocessing
+            "--steps.ramp_fit.save_opt=True",
+            "--steps.ramp_fit.opt_name=jw01094001002_02107_00001_nis.fits",
+            ]
+
+    Step.from_cmdline(args)
+
+
+@pytest.fixture(scope="module")
+def run_detector1_multiprocess_jump(rtdata_module):
+    """Run calwebb_detector1 pipeline on NIRISS imaging data."""
+    rtdata = rtdata_module
+
+    rtdata.get_data("niriss/imaging/jw01094001002_02107_00001_nis_uncal.fits")
+
+    # Run detector1 pipeline on an _uncal files
+    args = ["calwebb_detector1", rtdata.input,
+            "--steps.persistence.save_trapsfilled=False",
+            "--steps.dq_init.save_results=True",
+            "--steps.saturation.save_results=True",
+            "--steps.superbias.save_results=True",
+            "--steps.refpix.save_results=True",
+            "--steps.linearity.save_results=True",
+            "--steps.dark_current.save_results=True",
+            "--steps.charge_migration.skip=False",
+            "--steps.charge_migration.save_results=True",
+            "--steps.jump.save_results=True",
+            "--steps.jump.maximum_cores=2", # Multiprocessing
+            "--steps.ramp_fit.skip=True",
+            ]
+
+    Step.from_cmdline(args)
+
+
 @pytest.fixture(scope="module")
 def run_detector1_with_clean_flicker_noise(rtdata_module):
     """Run detector1 pipeline on NIRISS imaging data with noise cleaning."""
@@ -67,6 +145,7 @@ def test_niriss_image_detector1(run_detector1, rtdata_module, fitsdiff_default_k
     _assert_is_same(rtdata_module, fitsdiff_default_kwargs, suffix, truth_dir)
 
 
+
 @pytest.mark.bigdata
 @pytest.mark.parametrize("suffix", ["cfn_clean_flicker_noise", "mask",
                                     "flicker_bkg", "flicker_noise",
@@ -110,6 +189,43 @@ def test_niriss_tweakreg_no_sources(rtdata, fitsdiff_default_kwargs):
             result.shelve(model, modify=False)
 
 
+@pytest.mark.bigdata
+def test_niriss_image_detector1_multiprocess_rate(
+        run_detector1_multiprocess_rate, rtdata_module, fitsdiff_default_kwargs):
+    """
+    Runs test_niriss_image_detector1[rate], but with ramp fitting run with multiprocessing
+    on two processors.
+    """
+    truth_dir = 'test_niriss_image'
+    # fitsdiff_default_kwargs["numdiffs"] = 10
+    _assert_is_same(rtdata_module, fitsdiff_default_kwargs, "rate", truth_dir)
+
+
+@pytest.mark.bigdata
+@pytest.mark.parametrize("suffix", ["rate", "fitopt"])
+def test_niriss_image_detector1_multiprocess_rate_save_opt(
+        run_detector1_multiprocess_rate_save_opt, rtdata_module, fitsdiff_default_kwargs, suffix):
+    """
+    Runs test_niriss_image_detector1[rate], but with ramp fitting run with multiprocessing
+    on two processors and the optional results product.
+    """
+    truth_dir = 'test_niriss_image'
+    # fitsdiff_default_kwargs["numdiffs"] = 10
+    _assert_is_same(rtdata_module, fitsdiff_default_kwargs, suffix, truth_dir)
+
+
+@pytest.mark.bigdata
+def test_niriss_image_detector1_multiprocess_jump(
+        run_detector1_multiprocess_jump, rtdata_module, fitsdiff_default_kwargs):
+    """
+    Runs test_niriss_image_detector1[rate], but with ramp fitting run with multiprocessing
+    on two processors.
+    """
+    truth_dir = 'test_niriss_image'
+    # fitsdiff_default_kwargs["numdiffs"] = 10
+    _assert_is_same(rtdata_module, fitsdiff_default_kwargs, "jump", truth_dir)
+
+
 def _assert_is_same(rtdata_module, fitsdiff_default_kwargs, suffix, truth_dir):
     """Assertion helper for the above tests"""
     rtdata = rtdata_module