diff --git a/.coveragerc b/.coveragerc
index 1f2be51..3342379 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -4,7 +4,7 @@ source = .
 
 omit =
   # TODO
-  app.py
+  dp_creator_ii/app/*
 
 # More strict: Check transitions between lines, not just individual lines.
 # TODO: branch = True
diff --git a/dp_creator_ii/app/__init__.py b/dp_creator_ii/app/__init__.py
new file mode 100644
index 0000000..f636d97
--- /dev/null
+++ b/dp_creator_ii/app/__init__.py
@@ -0,0 +1,23 @@
+from shiny import App, ui
+
+from dp_creator_ii.app import analysis_panel, dataset_panel, results_panel
+
+
+app_ui = ui.page_bootstrap(
+    ui.navset_tab(
+        dataset_panel.dataset_ui(),
+        analysis_panel.analysis_ui(),
+        results_panel.results_ui(),
+        id="top_level_nav",
+    ),
+    title="DP Creator II",
+)
+
+
+def server(input, output, session):
+    dataset_panel.dataset_server(input, output, session)
+    analysis_panel.analysis_server(input, output, session)
+    results_panel.results_server(input, output, session)
+
+
+app = App(app_ui, server)
diff --git a/dp_creator_ii/app/analysis_panel.py b/dp_creator_ii/app/analysis_panel.py
new file mode 100644
index 0000000..ff89a81
--- /dev/null
+++ b/dp_creator_ii/app/analysis_panel.py
@@ -0,0 +1,17 @@
+from shiny import ui, reactive
+
+
+def analysis_ui():
+    return ui.nav_panel(
+        "Perform Analysis",
+        "TODO: Define analysis",
+        ui.input_action_button("go_to_results", "Download results"),
+        value="analysis_panel",
+    )
+
+
+def analysis_server(input, output, session):
+    @reactive.effect
+    @reactive.event(input.go_to_results)
+    def go_to_results():
+        ui.update_navs("top_level_nav", selected="results_panel")
diff --git a/dp_creator_ii/app/dataset_panel.py b/dp_creator_ii/app/dataset_panel.py
new file mode 100644
index 0000000..d43d62b
--- /dev/null
+++ b/dp_creator_ii/app/dataset_panel.py
@@ -0,0 +1,34 @@
+from pathlib import Path
+import json
+from shiny import ui, reactive, render
+from dp_creator_ii import get_arg_parser
+
+
+def dataset_ui():
+    return ui.nav_panel(
+        "Select Dataset",
+        "TODO: Pick dataset",
+        ui.output_text("csv_path_text"),
+        ui.output_text("unit_of_privacy_text"),
+        ui.input_action_button("go_to_analysis", "Perform analysis"),
+        value="dataset_panel",
+    )
+
+
+def dataset_server(input, output, session):
+    args = get_arg_parser().parse_args()
+    csv_path = reactive.value(args.csv_path)
+    unit_of_privacy = reactive.value(args.unit_of_privacy)
+
+    @render.text
+    def csv_path_text():
+        return str(csv_path.get())
+
+    @render.text
+    def unit_of_privacy_text():
+        return str(unit_of_privacy.get())
+
+    @reactive.effect
+    @reactive.event(input.go_to_analysis)
+    def go_to_analysis():
+        ui.update_navs("top_level_nav", selected="analysis_panel")
diff --git a/dp_creator_ii/app.py b/dp_creator_ii/app/results_panel.py
similarity index 54%
rename from dp_creator_ii/app.py
rename to dp_creator_ii/app/results_panel.py
index 0d975a3..d774cd3 100644
--- a/dp_creator_ii/app.py
+++ b/dp_creator_ii/app/results_panel.py
@@ -1,31 +1,11 @@
-from shiny import App, ui, reactive, render
+from shiny import ui, render
 
 from dp_creator_ii import get_arg_parser
 from dp_creator_ii.template import make_notebook_py, make_script_py
 from dp_creator_ii.converters import convert_py_to_nb
 
 
-def dataset_panel():
-    return ui.nav_panel(
-        "Select Dataset",
-        "TODO: Pick dataset",
-        ui.output_text("csv_path_text"),
-        ui.output_text("unit_of_privacy_text"),
-        ui.input_action_button("go_to_analysis", "Perform analysis"),
-        value="dataset_panel",
-    )
-
-
-def analysis_panel():
-    return ui.nav_panel(
-        "Perform Analysis",
-        "TODO: Define analysis",
-        ui.input_action_button("go_to_results", "Download results"),
-        value="analysis_panel",
-    )
-
-
-def results_panel():
+def results_ui():
     return ui.nav_panel(
         "Download Results",
         "TODO: Download Results",
@@ -41,41 +21,7 @@ def results_panel():
     )
 
 
-app_ui = ui.page_bootstrap(
-    ui.navset_tab(
-        dataset_panel(),
-        analysis_panel(),
-        results_panel(),
-        id="top_level_nav",
-    ),
-    title="DP Creator II",
-)
-
-
-def server(input, output, session):
-    args = get_arg_parser().parse_args()
-
-    csv_path = reactive.value(args.csv_path)
-    unit_of_privacy = reactive.value(args.unit_of_privacy)
-
-    @render.text
-    def csv_path_text():
-        return str(csv_path.get())
-
-    @render.text
-    def unit_of_privacy_text():
-        return str(unit_of_privacy.get())
-
-    @reactive.effect
-    @reactive.event(input.go_to_analysis)
-    def go_to_analysis():
-        ui.update_navs("top_level_nav", selected="analysis_panel")
-
-    @reactive.effect
-    @reactive.event(input.go_to_results)
-    def go_to_results():
-        ui.update_navs("top_level_nav", selected="results_panel")
-
+def results_server(input, output, session):
     @render.download(
         filename="dp-creator-script.py",
         media_type="text/x-python",
@@ -115,6 +61,3 @@ async def download_notebook_executed():
         )
         notebook_nb = convert_py_to_nb(notebook_py, execute=True)
         yield notebook_nb
-
-
-app = App(app_ui, server)
diff --git a/dp_creator_ii/tests/test_app.py b/dp_creator_ii/tests/test_app.py
index ec1ea58..684af42 100644
--- a/dp_creator_ii/tests/test_app.py
+++ b/dp_creator_ii/tests/test_app.py
@@ -3,7 +3,7 @@
 from shiny.pytest import create_app_fixture
 
 
-app = create_app_fixture("../app.py")
+app = create_app_fixture("../app/__init__.py")
 
 
 # TODO: Why is incomplete coverage reported here?