diff --git a/CHANGELOG.md b/CHANGELOG.md
index e95f37c..c08c14a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Added
+
+- URN features
+-- To CompileToJsonSchema class: load_urn_schema_filenames option
+-- To CLI: --urn-schema-filename option
 
 ### Removed
 
diff --git a/compiletojsonschema/cli/__main__.py b/compiletojsonschema/cli/__main__.py
index 993fb33..7db05e6 100644
--- a/compiletojsonschema/cli/__main__.py
+++ b/compiletojsonschema/cli/__main__.py
@@ -18,6 +18,12 @@ def main():
         "--codelist-base-directory",
         help="Which directory we should look in for codelists",
     )
+    parser.add_argument(
+        "-u",
+        "--urn-schema-filename",
+        help="Filenames of additional schemas to load and refer to by URN later while processing the input file",
+        action="append",
+    )
 
     args = parser.parse_args()
 
@@ -25,5 +31,6 @@ def main():
         input_filename=args.input_file,
         set_additional_properties_false_everywhere=args.set_additional_properties_false_everywhere,
         codelist_base_directory=args.codelist_base_directory,
+        load_urn_schema_filenames=args.urn_schema_filename or [],
     )
     print(ctjs.get_as_string())
diff --git a/compiletojsonschema/compiletojsonschema.py b/compiletojsonschema/compiletojsonschema.py
index a670635..820b65c 100644
--- a/compiletojsonschema/compiletojsonschema.py
+++ b/compiletojsonschema/compiletojsonschema.py
@@ -1,4 +1,5 @@
 import csv
+import functools
 import json
 import os
 import pathlib
@@ -6,6 +7,16 @@
 from copy import deepcopy
 
 import jsonref
+import referencing
+
+
+def _jsonref_loader(uri, urn_registry=None):
+    if uri.startswith("urn:"):
+        if urn_registry and uri in urn_registry:
+            return urn_registry.contents(uri)
+        else:
+            raise Exception("URN {} not found".format(uri))
+    return jsonref.jsonloader(uri)
 
 
 class CompileToJsonSchema:
@@ -15,6 +26,7 @@ def __init__(
         set_additional_properties_false_everywhere=False,
         codelist_base_directory=None,
         input_schema=None,
+        load_urn_schema_filenames=[],
     ):
         if not isinstance(input_schema, dict) and not input_filename:
             raise Exception("Must pass input_filename or input_schema")
@@ -27,19 +39,35 @@ def __init__(
             self.codelist_base_directory = os.path.expanduser(codelist_base_directory)
         else:
             self.codelist_base_directory = os.getcwd()
+        self.load_urn_schema_filenames = load_urn_schema_filenames
 
     def get(self):
+        urn_registry = None
+        if self.load_urn_schema_filenames:
+            urn_registry = referencing.Registry()
+            for urn_schema_filename in self.load_urn_schema_filenames:
+                with open(urn_schema_filename) as fp:
+                    urn_schema_json = json.load(fp)
+                    urn_schema_obj = referencing.Resource.from_contents(urn_schema_json)
+                    urn_registry = urn_schema_obj @ urn_registry
+
         if self.input_filename:
             with open(self.input_filename) as fp:
                 resolved = jsonref.load(
                     fp,
+                    loader=functools.partial(
+                        _jsonref_loader, urn_registry=urn_registry
+                    ),
                     object_pairs_hook=OrderedDict,
                     base_uri=pathlib.Path(
                         os.path.realpath(self.input_filename)
                     ).as_uri(),
                 )
         elif isinstance(self.input_schema, dict):
-            resolved = jsonref.JsonRef.replace_refs(self.input_schema)
+            resolved = jsonref.JsonRef.replace_refs(
+                self.input_schema,
+                loader=functools.partial(_jsonref_loader, urn_registry=urn_registry),
+            )
         else:
             raise Exception("Must pass input_filename or input_schema")
 
diff --git a/docs/cli.rst b/docs/cli.rst
index 6dc3e1f..2488e1a 100644
--- a/docs/cli.rst
+++ b/docs/cli.rst
@@ -37,3 +37,15 @@ To enable this mode, pass the `--set-additional-properties-false-everywhere` or
 
     compiletojsonschema -s input.json
     compiletojsonschema --set-additional-properties-false-everywhere input.json
+
+
+URN Refs
+--------
+
+Pass the names of files to load. This can be used multiple times.
+
+.. code-block:: shell-session
+
+    compiletojsonschema -u library.json -u components.json schema.json
+    compiletojsonschema --urn-schema-filename library.json --urn-schema-filename components.json schema.json
+
diff --git a/docs/features.rst b/docs/features.rst
index 580618b..45a2c48 100644
--- a/docs/features.rst
+++ b/docs/features.rst
@@ -155,3 +155,52 @@ you may want to generate a strict version of your schema that doesn't allow any
 This can be used for testing - for example, checking your sample data does not have any additional properties.
 
 This is an optional mode, which defaults to off.
+
+URN Refs
+--------
+
+You can use URN's in refs.
+
+For example, if you have the `library.json` schema:
+
+.. code-block:: json
+
+    {
+      "$id": "urn:library",
+      "$schema": "https://json-schema.org/draft/2020-12/schema",
+      "$defs": {
+        "address": {
+          "type": "object",
+          "properties": {
+            "address": {
+              "type": "string"
+            }
+          }
+        }
+      }
+    }
+
+And a schema `schema.json`:
+
+.. code-block:: json
+
+    {
+      "$id": "urn:schema",
+      "$schema": "https://json-schema.org/draft/2020-12/schema",
+        "properties": {
+          "home_address": {
+            "$ref": "urn:library#/$defs/address"
+          },
+          "work_address": {
+            "$ref": "urn:library#/$defs/address"
+          }
+        }
+    }
+
+This will compile.
+
+To do so:
+
+* you should pass the actual schema file `schema.json` to the tool where processing should start.
+* you will need to make sure the tool knows about the other `library.json` file.
+
diff --git a/setup.py b/setup.py
index 502e2ed..fa4cb78 100644
--- a/setup.py
+++ b/setup.py
@@ -15,6 +15,7 @@
     install_requires=[
         "jsonref",
         "jsonschema",
+        "referencing",
     ],
     extras_require={
         "test": extras_require_test,
diff --git a/tests/fixtures/urn/library.json b/tests/fixtures/urn/library.json
new file mode 100644
index 0000000..96d19d9
--- /dev/null
+++ b/tests/fixtures/urn/library.json
@@ -0,0 +1,19 @@
+{
+  "$id": "urn:library",
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$defs": {
+    "address": {
+      "title": "An Address",
+      "description": "A Description",
+      "type": "object",
+      "properties": {
+        "address": {
+          "type": "string"
+        },
+        "country": {
+          "type": "string"
+        }
+      }
+    }
+  }
+}
diff --git a/tests/fixtures/urn/schema.json b/tests/fixtures/urn/schema.json
new file mode 100644
index 0000000..c607a15
--- /dev/null
+++ b/tests/fixtures/urn/schema.json
@@ -0,0 +1,16 @@
+{
+  "$id": "urn:schema",
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "properties": {
+      "home_address": {
+        "title": "Home Address",
+        "description": "Where the person lives",
+        "$ref": "urn:library#/$defs/address"
+      },
+      "work_address": {
+        "title": "Work Address",
+        "description": "Where the person works",
+        "$ref": "urn:library#/$defs/address"
+      }
+    }
+}
diff --git a/tests/test_urn.py b/tests/test_urn.py
new file mode 100644
index 0000000..6fd0ffb
--- /dev/null
+++ b/tests/test_urn.py
@@ -0,0 +1,56 @@
+import json
+import os
+
+import jsonref
+import pytest
+
+from compiletojsonschema.compiletojsonschema import CompileToJsonSchema
+
+
+def test_urn():
+
+    input_filename = os.path.join(
+        os.path.dirname(os.path.realpath(__file__)),
+        "fixtures",
+        "urn",
+        "schema.json",
+    )
+
+    lib_filename = os.path.join(
+        os.path.dirname(os.path.realpath(__file__)),
+        "fixtures",
+        "urn",
+        "library.json",
+    )
+
+    ctjs = CompileToJsonSchema(
+        input_filename=input_filename, load_urn_schema_filenames=[lib_filename]
+    )
+    out_string = ctjs.get_as_string()
+    out = json.loads(out_string)
+
+    assert out["properties"]["work_address"]["title"] == "Work Address"
+    assert out["properties"]["work_address"]["description"] == "Where the person works"
+    assert (
+        out["properties"]["work_address"]["properties"]["address"]["type"] == "string"
+    )
+    assert out["properties"]["home_address"]["title"] == "Home Address"
+    assert out["properties"]["home_address"]["description"] == "Where the person lives"
+    assert (
+        out["properties"]["home_address"]["properties"]["address"]["type"] == "string"
+    )
+
+
+def test_urn_not_loaded():
+
+    input_filename = os.path.join(
+        os.path.dirname(os.path.realpath(__file__)),
+        "fixtures",
+        "urn",
+        "schema.json",
+    )
+
+    ctjs = CompileToJsonSchema(input_filename=input_filename)
+
+    with pytest.raises(jsonref.JsonRefError):
+        ctjs.get_as_string()