diff --git a/ssm.py b/ssm.py
index d8649bc..ee7d618 100644
--- a/ssm.py
+++ b/ssm.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import enum
 import os
 import pathlib
 import sys
@@ -28,6 +29,12 @@ class SSMPath(pathlib.PurePosixPath):
         return SSMPath(value)
 
 
+class SSMParameterType(str, enum.Enum):
+    String = "String"
+    SecureString = "SecureString"
+    StringList = "StringList"
+
+
 ProfileArg = typing.Annotated[str, typer.Argument(autocompletion=lambda: aws_profiles)]
 
 
@@ -103,7 +110,7 @@ def list_parameters(
 def set(
     profile: ProfileArg,
     path: str,
-    value: str,
+    values: list[str],
     secure: bool = False,
     overwrite: bool = False,
     description: typing.Annotated[str, typer.Option] = "",
@@ -112,12 +119,19 @@ def set(
 
     If --secure is used, it will be stored as a SecureString.
     """
+    if secure:
+        parameter_type = SSMParameterType.SecureString
+    elif len(values) > 1:
+        parameter_type = SSMParameterType.StringList
+    else:
+        parameter_type = SSMParameterType.String
+    value: str = ",".join(values)
     client = get_client(profile)
     try:
         client.put_parameter(
             Name=str(SSMPath(path)),
             Value=value,
-            Type="SecureString" if secure else "String",
+            Type=parameter_type.value,
             Overwrite=overwrite,
             Description=description,
         )