diff --git a/main.py b/main.py
index 5d6699f..7004567 100755
--- a/main.py
+++ b/main.py
@@ -7,13 +7,23 @@ from pathlib import Path
 
 def main():
     parser = argparse.ArgumentParser(
-        description="Convert a passwd file to a directory of systemd JSON user records.",
+        description="Convert a passwd/group/shadow file to a directory of systemd JSON user records.",
     )
     parser.add_argument(
         "passwd_file",
         type=Path,
         help="Path to the passwd file.",
     )
+    parser.add_argument(
+        "group_file",
+        type=Path,
+        help="Path to the group file.",
+    )
+    parser.add_argument(
+        "shadow_file",
+        type=Path,
+        help="Path to the shadow file.",
+    )
     parser.add_argument(
         "output_dir",
         type=Path,
@@ -22,10 +32,18 @@ def main():
     args = parser.parse_args()
 
     parsed_users = parse_passwd_file(args.passwd_file)
+    parsed_groups = parse_group_file(args.group_file)
+    parsed_shadow = parse_shadow_file(args.shadow_file)
 
     for user in parsed_users:
         print(json.dumps(user, indent=2))
 
+    for group in parsed_groups:
+        print(json.dumps(group, indent=2))
+
+    for shadow_entry in parsed_shadow:
+        print(json.dumps(shadow_entry, indent=2))
+
 
 def parse_passwd_file(passwd_file: Path) -> list[dict]:
     users = []
@@ -41,7 +59,7 @@ def parse_passwd_file(passwd_file: Path) -> list[dict]:
                 "name": parts[0],
                 "uid": int(parts[2]),
                 "gid": int(parts[3]),
-                "gecos": parse_gecos(parts[4]),
+                "gecos": parse_passwd_gecos(parts[4]),
                 "home": parts[5],
                 "shell": parts[6],
             }
@@ -49,7 +67,7 @@ def parse_passwd_file(passwd_file: Path) -> list[dict]:
     return users
 
 
-def parse_gecos(gecos: str) -> dict:
+def parse_passwd_gecos(gecos: str) -> dict:
     parts = gecos.split(",")
     return {
         "full_name": parts[0] if len(parts) > 0 else "",
@@ -60,5 +78,49 @@ def parse_gecos(gecos: str) -> dict:
     }
 
 
+def parse_group_file(group_file: Path) -> list[dict]:
+    groups = []
+    with group_file.open("r") as f:
+        for line in f:
+            if line.startswith("#") or not line.strip():
+                continue
+            parts = line.strip().split(":")
+            if len(parts) < 4:
+                print(f"Warning: Skipping malformed line: {line.strip()}")
+                continue
+            group = {
+                "name": parts[0],
+                "gid": int(parts[2]),
+                "members": parts[3].split(",") if parts[3] else [],
+            }
+            groups.append(group)
+    return groups
+
+
+def parse_shadow_file(shadow_file: Path) -> list[dict]:
+    shadow_entries = []
+    with shadow_file.open("r") as f:
+        for line in f:
+            if line.startswith("#") or not line.strip():
+                continue
+            parts = line.strip().split(":")
+            if len(parts) < 9:
+                print(f"Warning: Skipping malformed line: {line.strip()}")
+                continue
+            shadow_entry = {
+                "name": parts[0],
+                "password": parts[1],
+                "last_change": int(parts[2]) if parts[2].isdigit() else None,
+                "min_days": int(parts[3]) if parts[3].isdigit() else None,
+                "max_days": int(parts[4]) if parts[4].isdigit() else None,
+                "warn_days": int(parts[5]) if parts[5].isdigit() else None,
+                "inactive_days": int(parts[6]) if parts[6].isdigit() else None,
+                "expire_date": int(parts[7]) if parts[7].isdigit() else None,
+                "reserved": parts[8],
+            }
+            shadow_entries.append(shadow_entry)
+    return shadow_entries
+
+
 if __name__ == "__main__":
     main()
diff --git a/test_assets/test.group b/test_assets/test.group
new file mode 100644
index 0000000..c8b3962
--- /dev/null
+++ b/test_assets/test.group
@@ -0,0 +1,28 @@
+root:x:0:
+daemon:x:1:
+bin:x:2:
+sys:x:3:
+games:x:60:
+man:x:12:
+lp:x:7:
+mail:x:8:
+news:x:9:
+uucp:x:10:
+proxy:x:13:
+www-data:x:33:
+backup:x:34:
+list:x:38:
+irc:x:39:
+gnats:x:41:
+nobody:x:65534:
+systemd-timesync:x:101:
+systemd-network:x:103:user1
+systemd-resolve:x:104:user1,user2
+messagebus:x:105:
+avahi:x:109:
+saned:x:112:
+xrdp:x:114:
+
+user1:x:1000:
+user2:x:1001:
+user3:x:1002:
diff --git a/test.passwd b/test_assets/test.passwd
similarity index 100%
rename from test.passwd
rename to test_assets/test.passwd
diff --git a/test_assets/test.shadow b/test_assets/test.shadow
new file mode 100644
index 0000000..31c9e36
--- /dev/null
+++ b/test_assets/test.shadow
@@ -0,0 +1,30 @@
+root:!*:1::::::
+daemon:!*:1::::::
+bin:!*:1::::::
+sys:!*:1::::::
+sync:!*:1::::::
+games:!*:1::::::
+man:!*:1::::::
+lp:!*:1::::::
+mail:!*:1::::::
+news:!*:1::::::
+uucp:!*:1::::::
+proxy:!*:1::::::
+www-data:!*:1::::::
+backup:!*:1::::::
+list:!*:1::::::
+irc:!*:1::::::
+gnats:!*:1::::::
+nobody:!*:1::::::
+_apt:!*:1::::::
+systemd-timesync:!*:1::::::
+systemd-network:!*:1::::::
+systemd-resolve:!*:1::::::
+messagebus:!*:1::::::
+avahi:!*:1::::::
+saned:!*:1::::::
+xrdp:!*:1::::::
+
+user1:$y$j9T$gfNWp8nhIYxJtL7yy7myb0$LAsxtu.24imcyO5CH0xOL/G6Ii5LlLWnAJ.XL8CPYv3:20000::::::
+user2:$y$j9T$90l8J./nwd7sRU/HOyVtg.$f/M1K5evMFp0K2NYIjN257YHMUlg0wG/Sst1LXy2g3C:20001::::::
+user3:$y$j9T$lekKJIXaaL/24EvKehybL1$MSS0OHfiCTgcdExEDqaEsGFaYOphApGVV8fXrs.U1C5:20002::::::