diff --git a/pyproject.toml b/pyproject.toml
index 59ef225f..058e151f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,7 +19,7 @@ dependencies = [
     "dask[distributed]",
     "deprecated",
     "healpy",
-    "hipscat >= 0.1.2",
+    "hipscat >= 0.1.5",
     "ipykernel", # Support for Jupyter notebooks
     "pandas < 2.1.0",
     "pyarrow",
diff --git a/src/hipscat_import/catalog/arguments.py b/src/hipscat_import/catalog/arguments.py
index fb43b35b..81703bb3 100644
--- a/src/hipscat_import/catalog/arguments.py
+++ b/src/hipscat_import/catalog/arguments.py
@@ -40,6 +40,8 @@ class ImportArguments(RuntimeArguments):
     """column for right ascension"""
     dec_column: str = "dec"
     """column for declination"""
+    use_hipscat_index: bool = False
+    """use an existing hipscat spatial index as the position, instead of ra/dec"""
     id_column: str = "id"
     """column for survey identifier, or other sortable column"""
     add_hipscat_index: bool = True
@@ -133,6 +135,7 @@ def additional_runtime_provenance_info(self) -> dict:
             "input_file_list": self.input_file_list,
             "ra_column": self.ra_column,
             "dec_column": self.dec_column,
+            "use_hipscat_index": self.use_hipscat_index,
             "id_column": self.id_column,
             "constant_healpix_order": self.constant_healpix_order,
             "highest_healpix_order": self.highest_healpix_order,
diff --git a/src/hipscat_import/catalog/map_reduce.py b/src/hipscat_import/catalog/map_reduce.py
index 97ed8def..41e06db5 100644
--- a/src/hipscat_import/catalog/map_reduce.py
+++ b/src/hipscat_import/catalog/map_reduce.py
@@ -6,6 +6,7 @@
 import pyarrow.parquet as pq
 from hipscat import pixel_math
 from hipscat.io import FilePointer, file_io, paths
+from hipscat.pixel_math.hipscat_id import HIPSCAT_ID_COLUMN, hipscat_id_to_healpix
 
 from hipscat_import.catalog.file_readers import InputReader
 from hipscat_import.catalog.resume_plan import ResumePlan
@@ -53,6 +54,7 @@ def _iterate_input_file(
     highest_order,
     ra_column,
     dec_column,
+    use_hipscat_index = False,
 ):
     """Helper function to handle input file reading and healpix pixel calculation"""
     if not file_reader:
@@ -61,18 +63,28 @@ def _iterate_input_file(
     required_columns = [ra_column, dec_column]
 
     for chunk_number, data in enumerate(file_reader.read(input_file)):
-        if not all(x in data.columns for x in required_columns):
-            raise ValueError(
-                f"Invalid column names in input file: {ra_column}, {dec_column} not in {input_file}"
+        if use_hipscat_index:
+            if data.index.name == HIPSCAT_ID_COLUMN:
+                mapped_pixels = hipscat_id_to_healpix(data.index, target_order=highest_order)
+            elif HIPSCAT_ID_COLUMN in data.columns:
+                mapped_pixels = hipscat_id_to_healpix(data[HIPSCAT_ID_COLUMN], target_order=highest_order)
+            else:
+                raise ValueError(
+                    f"Invalid column names in input file: {HIPSCAT_ID_COLUMN} not in {input_file}"
+                )
+        else:
+            if not all(x in data.columns for x in required_columns):
+                raise ValueError(
+                    f"Invalid column names in input file: {', '.join(required_columns)} not in {input_file}"
+                )
+            # Set up the pixel data
+            mapped_pixels = hp.ang2pix(
+                2**highest_order,
+                data[ra_column].values,
+                data[dec_column].values,
+                lonlat=True,
+                nest=True,
             )
-        # Set up the pixel data
-        mapped_pixels = hp.ang2pix(
-            2**highest_order,
-            data[ra_column].values,
-            data[dec_column].values,
-            lonlat=True,
-            nest=True,
-        )
         yield chunk_number, data, mapped_pixels
 
 
@@ -84,6 +96,7 @@ def map_to_pixels(
     highest_order,
     ra_column,
     dec_column,
+    use_hipscat_index = False
 ):
     """Map a file of input objects to their healpix pixels.
 
@@ -107,7 +120,7 @@ def map_to_pixels(
     """
     histo = pixel_math.empty_histogram(highest_order)
     for _, _, mapped_pixels in _iterate_input_file(
-        input_file, file_reader, highest_order, ra_column, dec_column
+        input_file, file_reader, highest_order, ra_column, dec_column, use_hipscat_index
     ):
         mapped_pixel, count_at_pixel = np.unique(mapped_pixels, return_counts=True)
         mapped_pixel = mapped_pixel.astype(np.int64)
@@ -125,6 +138,7 @@ def split_pixels(
     cache_shard_path: FilePointer,
     resume_path: FilePointer,
     alignment=None,
+    use_hipscat_index = False,
 ):
     """Map a file of input objects to their healpix pixels and split into shards.
 
@@ -145,7 +159,7 @@ def split_pixels(
         FileNotFoundError: if the file does not exist, or is a directory
     """
     for chunk_number, data, mapped_pixels in _iterate_input_file(
-        input_file, file_reader, highest_order, ra_column, dec_column
+        input_file, file_reader, highest_order, ra_column, dec_column, use_hipscat_index
     ):
         aligned_pixels = alignment[mapped_pixels]
         unique_pixels, unique_inverse = np.unique(aligned_pixels, return_inverse=True)
@@ -181,6 +195,7 @@ def reduce_pixel_shards(
     ra_column,
     dec_column,
     id_column,
+    use_hipscat_index = False,
     add_hipscat_index=True,
     delete_input_files=True,
     use_schema_file="",
@@ -260,8 +275,8 @@ def reduce_pixel_shards(
     dataframe = merged_table.to_pandas()
     if id_column:
         dataframe = dataframe.sort_values(id_column)
-    if add_hipscat_index:
-        dataframe["_hipscat_index"] = pixel_math.compute_hipscat_id(
+    if add_hipscat_index and not use_hipscat_index:
+        dataframe[HIPSCAT_ID_COLUMN] = pixel_math.compute_hipscat_id(
             dataframe[ra_column].values,
             dataframe[dec_column].values,
         )
@@ -278,7 +293,7 @@ def reduce_pixel_shards(
         ## If we had a meaningful index before, preserve it as a column.
         if _has_named_index(dataframe):
             dataframe = dataframe.reset_index()
-        dataframe = dataframe.set_index("_hipscat_index").sort_index()
+        dataframe = dataframe.set_index(HIPSCAT_ID_COLUMN).sort_index()
     dataframe.to_parquet(destination_file)
 
     del dataframe, merged_table, tables
diff --git a/src/hipscat_import/catalog/run_import.py b/src/hipscat_import/catalog/run_import.py
index 218bd539..36a7476c 100644
--- a/src/hipscat_import/catalog/run_import.py
+++ b/src/hipscat_import/catalog/run_import.py
@@ -35,6 +35,7 @@ def _map_pixels(args, client):
                 highest_order=args.mapping_healpix_order,
                 ra_column=args.ra_column,
                 dec_column=args.dec_column,
+                use_hipscat_index=args.use_hipscat_index,
             )
         )
     args.resume_plan.wait_for_mapping(futures)
@@ -62,6 +63,7 @@ def _split_pixels(args, alignment_future, client):
                 cache_shard_path=args.tmp_path,
                 resume_path=args.resume_plan.tmp_path,
                 alignment=alignment_future,
+                use_hipscat_index=args.use_hipscat_index,
             )
         )
 
@@ -96,6 +98,7 @@ def _reduce_pixels(args, destination_pixel_map, client):
                 id_column=args.id_column,
                 add_hipscat_index=args.add_hipscat_index,
                 use_schema_file=args.use_schema_file,
+                use_hipscat_index=args.use_hipscat_index,
             )
         )
 
diff --git a/src/hipscat_import/index/map_reduce.py b/src/hipscat_import/index/map_reduce.py
index a7cb5399..e446a2a9 100644
--- a/src/hipscat_import/index/map_reduce.py
+++ b/src/hipscat_import/index/map_reduce.py
@@ -4,6 +4,7 @@
 import numpy as np
 from dask.distributed import progress, wait
 from hipscat.io import file_io
+from hipscat.pixel_math.hipscat_id import HIPSCAT_ID_COLUMN
 
 
 def create_index(args):
@@ -31,7 +32,7 @@ def create_index(args):
         data["Npix"] = data["Npix"].astype(np.int32)
     data = data.reset_index()
     if not args.include_hipscat_index:
-        data = data.drop(columns=["_hipscat_index"])
+        data = data.drop(columns=[HIPSCAT_ID_COLUMN])
     data = data.repartition(partition_size=args.compute_partition_size)
     data = data.set_index(args.indexing_column)
     result = data.to_parquet(
diff --git a/tests/hipscat_import/catalog/test_map_reduce.py b/tests/hipscat_import/catalog/test_map_reduce.py
index 6168e4d9..0a2d36a5 100644
--- a/tests/hipscat_import/catalog/test_map_reduce.py
+++ b/tests/hipscat_import/catalog/test_map_reduce.py
@@ -134,6 +134,38 @@ def test_map_headers(tmp_path, formats_headers_csv):
     assert (result == expected).all()
 
 
+def test_map_with_hipscat_index(tmp_path, formats_dir, small_sky_single_file):
+    os.makedirs(os.path.join(tmp_path, "histograms"))
+    input_file = os.path.join(formats_dir, "hipscat_index.csv")
+    mr.map_to_pixels(
+        input_file=input_file,
+        file_reader=get_file_reader("csv"),
+        highest_order=0,
+        ra_column="NOPE",
+        dec_column="NOPE",
+        use_hipscat_index=True,  # radec don't matter. just use existing index
+        resume_path=tmp_path,
+        mapping_key="map_0",
+    )
+
+    expected = hist.empty_histogram(0)
+    expected[11] = 131
+
+    result = read_partial_histogram(tmp_path, "map_0")
+    npt.assert_array_equal(result, expected)
+
+    with pytest.raises(ValueError, match="_hipscat_index not in"):
+        mr.map_to_pixels(
+            input_file=small_sky_single_file,
+            file_reader=get_file_reader("csv"),
+            highest_order=0,
+            ra_column="NOPE",
+            dec_column="NOPE",
+            use_hipscat_index=True,  # no pre-existing index! expect failure.
+            resume_path=tmp_path,
+            mapping_key="map_0",
+        )
+
 def test_map_with_schema(tmp_path, mixed_schema_csv_dir, mixed_schema_csv_parquet):
     """Test loading the a file when using a parquet schema file for dtypes"""
     os.makedirs(os.path.join(tmp_path, "histograms"))
@@ -161,7 +193,6 @@ def test_map_with_schema(tmp_path, mixed_schema_csv_dir, mixed_schema_csv_parque
     npt.assert_array_equal(result, expected)
     assert (result == expected).all()
 
-
 def test_map_small_sky_order0(tmp_path, small_sky_single_file):
     """Test loading the small sky catalog and partitioning each object into the same large bucket"""
     os.makedirs(os.path.join(tmp_path, "histograms"))
diff --git a/tests/hipscat_import/catalog/test_run_round_trip.py b/tests/hipscat_import/catalog/test_run_round_trip.py
index e195008c..00901ad5 100644
--- a/tests/hipscat_import/catalog/test_run_round_trip.py
+++ b/tests/hipscat_import/catalog/test_run_round_trip.py
@@ -356,3 +356,59 @@ def read(self, input_file):
 
     expected_ids = [*range(700, 831)]
     assert_parquet_file_ids(output_file, "id", expected_ids)
+
+
+@pytest.mark.dask
+def test_import_hipscat_index(
+    dask_client,
+    formats_dir,
+    assert_parquet_file_ids,
+    tmp_path,
+):
+    """Test basic execution, using a previously-computed _hipscat_index column for spatial partitioning."""
+    ## First, let's just check the assumptions we have about our input file:
+    ## - should have _hipscat_index as the indexed column
+    ## - should NOT have any columns like "ra" or "dec"
+    input_file = os.path.join(formats_dir, "hipscat_index.parquet")
+
+    expected_ids = [*range(700, 831)]
+    assert_parquet_file_ids(input_file, "id", expected_ids)
+
+    data_frame = pd.read_parquet(input_file, engine="pyarrow")
+    assert data_frame.index.name == "_hipscat_index"
+    npt.assert_array_equal(data_frame.columns, ["id"])
+
+    args = ImportArguments(
+        output_catalog_name="using_hipscat_index",
+        input_file_list=[input_file],
+        input_format="parquet",
+        output_path=tmp_path,
+        dask_tmp=tmp_path,
+        use_hipscat_index=True,
+        add_hipscat_index=False,
+        highest_healpix_order=2,
+        pixel_threshold=3_000,
+        progress_bar=False,
+        id_column="_hipscat_index",
+    )
+
+    runner.run(args, dask_client)
+
+    # Check that the catalog metadata file exists
+    catalog = Catalog.read_from_hipscat(args.catalog_path)
+    assert catalog.on_disk
+    assert catalog.catalog_path == args.catalog_path
+    assert catalog.catalog_info.total_rows == 131
+    assert len(catalog.get_healpix_pixels()) == 1
+
+    # Check that the catalog parquet file exists and contains correct object IDs
+    output_file = os.path.join(args.catalog_path, "Norder=0", "Dir=0", "Npix=11.parquet")
+
+    expected_ids = [*range(700, 831)]
+    assert_parquet_file_ids(output_file, "id", expected_ids)
+    data_frame = pd.read_parquet(output_file, engine="pyarrow")
+    assert data_frame.index.name == "_hipscat_index"
+    npt.assert_array_equal(
+        data_frame.columns,
+        ["id", "Norder", "Dir", "Npix"],
+    )
diff --git a/tests/hipscat_import/data/test_formats/hipscat_index.csv b/tests/hipscat_import/data/test_formats/hipscat_index.csv
new file mode 100644
index 00000000..153091e5
--- /dev/null
+++ b/tests/hipscat_import/data/test_formats/hipscat_index.csv
@@ -0,0 +1,132 @@
+_hipscat_index,id,ra,dec,ra_error,dec_error,Norder,Dir,Npix
+12749688880727326720,707,308.5,-69.5,0,0,0,0,11
+12751184493818150912,792,320.5,-69.5,0,0,0,0,11
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