diff --git a/build/lib/pen_tracker/engine.py b/build/lib/pen_tracker/engine.py
index 90f7fbb..8444a3f 100644
--- a/build/lib/pen_tracker/engine.py
+++ b/build/lib/pen_tracker/engine.py
@@ -24,7 +24,12 @@ class Pen:
 class PenTracker:
     def __init__(self, storage_file: str = None):
         if storage_file is None:
-            storage_file = os.getenv('PEN_TRACKER_CSV', 'Pens.csv')
+            storage_file = os.getenv('PEN_TRACKER_CSV')
+            if storage_file is None:
+                data_home = os.getenv('XDG_DATA_HOME', os.path.expanduser('~/.local/share'))
+                app_data_dir = os.path.join(data_home, 'pen-tracker')
+                os.makedirs(app_data_dir, exist_ok=True)
+                storage_file = os.path.join(app_data_dir, 'pens.csv')
         self.storage_file = storage_file
         self.headers = [
             'Make', 'Model', 'Date-Purchased', 'Vendor', 'Nib',
diff --git a/build/lib/pen_tracker/tui.py b/build/lib/pen_tracker/tui.py
index 8de1846..ced7649 100644
--- a/build/lib/pen_tracker/tui.py
+++ b/build/lib/pen_tracker/tui.py
@@ -99,7 +99,7 @@ class PenTrackerApp(App):
         yield Footer()
 
     def on_mount(self) -> None:
-        self.tracker = PenTracker('Pens.csv')
+        self.tracker = PenTracker()
         self._refresh_table()
 
     def _refresh_table(self):
diff --git a/pyproject.toml b/pyproject.toml
index 6495605..e5ccc2e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pen-tracker"
-version = "0.2.0"
+version = "0.3.0"
 authors = [
   { name="Don Harper", email="don@donharper.org" },
 ]
diff --git a/src/pen_tracker.egg-info/PKG-INFO b/src/pen_tracker.egg-info/PKG-INFO
index f5ef874..83ea7ac 100644
--- a/src/pen_tracker.egg-info/PKG-INFO
+++ b/src/pen_tracker.egg-info/PKG-INFO
@@ -1,6 +1,6 @@
 Metadata-Version: 2.4
 Name: pen-tracker
-Version: 0.2.0
+Version: 0.3.0
 Summary: A fountain pen collection tracker.
 Author-email: Don Harper <don@donharper.org>
 Requires-Python: >=3.8
@@ -19,6 +19,12 @@ A simple fountain pen collection tracker.
 pip install .
 ```
 
+## Data Storage
+
+Pen data is stored in `~/.local/share/pen-tracker/pens.csv` by default, following XDG Base Directory specification. The directory is created automatically if it doesn't exist.
+
+You can override the location by setting the `PEN_TRACKER_CSV` environment variable.
+
 ## Usage
 
 ### CLI