diff --git a/bin.src/imsim.py b/bin.src/imsim.py
index 7da87c2a..2cfd1946 100755
--- a/bin.src/imsim.py
+++ b/bin.src/imsim.py
@@ -30,6 +30,8 @@
                     help='disable sensor effects')
 parser.add_argument('--file_id', type=str, default=None,
                     help='ID string to use for checkpoint and centroid filenames.')
+parser.add_argument('--create_centroid_file', default=False, action="store_true",
+                    help='Write centroid file(s).')
 parser.add_argument('--seed', type=int, default=267,
                     help='integer used to seed random number generator')
 parser.add_argument('--processes', type=int, default=1,
@@ -43,7 +45,7 @@
 psf = desc.imsim.make_psf(args.psf, obs_md, log_level=args.log_level)
 
 sensor_list = args.sensors.split('^') if args.sensors is not None \
-              else args.sensors
+    else args.sensors
 
 apply_sensor_model = not args.disable_sensor_model
 
@@ -55,6 +57,7 @@
                                 outdir=args.outdir,
                                 sensor_list=sensor_list,
                                 apply_sensor_model=apply_sensor_model,
+                                create_centroid_file=args.create_centroid_file,
                                 file_id=args.file_id,
                                 log_level=args.log_level)
 
diff --git a/data/default_imsim_configs b/data/default_imsim_configs
index a293f501..b86a40ca 100644
--- a/data/default_imsim_configs
+++ b/data/default_imsim_configs
@@ -6,6 +6,7 @@ full_well = 1e5
 
 [persistence]
 eimage_prefix = lsst_e_
+centroid_prefix = centroid_
 
 [cosmic_rays]
 ccd_rate = 8
diff --git a/python/desc/imsim/ImageSimulator.py b/python/desc/imsim/ImageSimulator.py
index b448ae18..119680da 100644
--- a/python/desc/imsim/ImageSimulator.py
+++ b/python/desc/imsim/ImageSimulator.py
@@ -29,6 +29,7 @@
 # image_simulator to self so that it is available in the callbacks.
 image_simulator = None
 
+
 class ImageSimulator:
     """
     Class to manage the parallel simulation of sensors using the
@@ -36,7 +37,7 @@ class ImageSimulator:
     """
     def __init__(self, instcat, psf, numRows=None, config=None, seed=267,
                  outdir='fits', sensor_list=None, apply_sensor_model=True,
-                 file_id=None, log_level='WARN'):
+                 create_centroid_file=False, file_id=None, log_level='WARN'):
         """
         Parameters
         ----------
@@ -69,6 +70,7 @@ def __init__(self, instcat, psf, numRows=None, config=None, seed=267,
             Logging level ('DEBUG', 'INFO', 'WARN', 'ERROR', 'CRITICAL').
         """
         self.config = read_config(config)
+        self.create_centroid_file = create_centroid_file
         self.psf = psf
         self.outdir = outdir
         self.obs_md, self.phot_params, sources \
@@ -125,6 +127,11 @@ def _make_gs_interpreters(self, seed, sensor_list, file_id):
                                         self.phot_params,
                                         self.obs_md)
 
+            if self.create_centroid_file:
+                self.gs_interpreters[det_name].centroid_base_name = \
+                    os.path.join(self.outdir,
+                                 self.config['persistence']['centroid_prefix'])
+
     @staticmethod
     def checkpoint_file(file_id, det_name):
         """
@@ -164,7 +171,7 @@ def eimage_file(self, det_name):
         prefix = self.config['persistence']['eimage_prefix']
         obsHistID = str(self.obs_md.OpsimMetaData['obshistID'])
         return os.path.join(self.outdir, prefix + '_'.join(
-            (obsHistID, detector.fileName, self.obs_md.bandpass +'.fits')))
+            (obsHistID, detector.fileName, self.obs_md.bandpass + '.fits')))
 
     def run(self, processes=1, wait_time=None):
         """
@@ -280,6 +287,11 @@ def __call__(self, gs_objects):
         gs_interpreter.writeImages(nameRoot=os.path.join(outdir, prefix)
                                    + obsHistID)
 
+        # Write out the centroid files if they were made.
+        gs_interpreter.write_centroid_files()
+        gs_interpreter.close_centroid_files()
+
+
 #        # The image for the sensor-visit has been drawn, so delete the
 #        # checkpoint file.
 #        os.remove(gs_interpreter.checkpoint_file)