diff --git a/incorporealcms/__init__.py b/incorporealcms/__init__.py
index 45ceb25..726eaa3 100644
--- a/incorporealcms/__init__.py
+++ b/incorporealcms/__init__.py
@@ -45,7 +45,10 @@ def create_app(instance_path=None, test_config=None):
         return send_from_directory(os.path.join(app.instance_path, app.config['MEDIA_DIR']),
                                    filename)
 
-    from . import pages
+    from . import error_pages, pages
     app.register_blueprint(pages.bp)
+    app.register_error_handler(400, error_pages.bad_request)
+    app.register_error_handler(404, error_pages.page_not_found)
+    app.register_error_handler(500, error_pages.internal_server_error)
 
     return app
diff --git a/incorporealcms/error_pages.py b/incorporealcms/error_pages.py
new file mode 100644
index 0000000..5034fab
--- /dev/null
+++ b/incorporealcms/error_pages.py
@@ -0,0 +1,17 @@
+"""Error page views for 400, 404, etc."""
+from incorporealcms.lib import render
+
+
+def bad_request(error):
+    """Display 400 error messaging."""
+    return render('400.html'), 400
+
+
+def internal_server_error(error):
+    """Display 500 error messaging."""
+    return render('500.html'), 500
+
+
+def page_not_found(error):
+    """Display 404 error messaging."""
+    return render('404.html'), 404
diff --git a/incorporealcms/templates/400.html b/incorporealcms/templates/400.html
new file mode 100644
index 0000000..5f629bf
--- /dev/null
+++ b/incorporealcms/templates/400.html
@@ -0,0 +1,14 @@
+{% extends "base.html" %}
+
+{% block header %}
+<div class="header">
+    <a href="/">{{ config.TITLE_SUFFIX }}</a>
+</div>
+{% endblock %}
+
+{% block body %}
+<div class="content">
+    <h1>BAD REQUEST</h1>
+    <p>You're doing something you're not supposed to. Stop it?</p>
+</div>
+{% endblock %}
diff --git a/incorporealcms/templates/404.html b/incorporealcms/templates/404.html
new file mode 100644
index 0000000..bac3191
--- /dev/null
+++ b/incorporealcms/templates/404.html
@@ -0,0 +1,19 @@
+{% extends "base.html" %}
+
+{% block header %}
+<div class="header">
+    <a href="/">{{ config.TITLE_SUFFIX }}</a>
+</div>
+{% endblock %}
+
+{% block body %}
+<div class="content">
+    <h1>NOT FOUND</h1>
+    <p>Sorry, <b><tt>{{ request.path }}</tt></b> does not seem to exist, at least not anymore.</p>
+    <p>It's possible you followed a dead link on this site, in which case I would appreciate it if you could email me via:
+    bss @ &lt;this domain&gt; and I can take a look. I make an effort to symlink old content to its new location,
+    so old links and URLs should, generally speaking, work.</p>
+    <p>Otherwise, I suggest you go <a href="/">to the index</a> and navigate your way (hopefully) to what
+    you're looking for.</p>
+</div>
+{% endblock %}
diff --git a/incorporealcms/templates/500.html b/incorporealcms/templates/500.html
new file mode 100644
index 0000000..68341a3
--- /dev/null
+++ b/incorporealcms/templates/500.html
@@ -0,0 +1,14 @@
+{% extends "base.html" %}
+
+{% block header %}
+<div class="header">
+    <a href="/">{{ config.TITLE_SUFFIX }}</a>
+</div>
+{% endblock %}
+
+{% block body %}
+<div class="content">
+    <h1>INTERNAL SERVER ERROR</h1>
+    <p>Something bad happened! Please email me at bss @ &lt;this domain&gt; and tell me what happened.</p>
+</div>
+{% endblock %}
diff --git a/incorporealcms/templates/base.html b/incorporealcms/templates/base.html
index d2772ab..e15878f 100644
--- a/incorporealcms/templates/base.html
+++ b/incorporealcms/templates/base.html
@@ -12,6 +12,7 @@
 <link rel="icon" href="{{ url_for('static', filename='img/favicon.png') }}">
 
 <div class="site-wrap">
+    {% block header %}
     <div class="header">
         <div class="nav">
             {% for nav in navs %}
@@ -24,11 +25,14 @@
             <a href="?style=light">[light]</a>
         </div>
     </div>
+    {% endblock %}
+    {% block body %}
     <div class="content">
         {{ content }}
     </div>
     <footer>
         <i>Last modified: {{ mtime }}</i>
     </footer>
+    {% endblock %}
 </div>
 </html>
diff --git a/tests/functional_tests.py b/tests/functional_tests.py
index bb6ef20..6353ac4 100644
--- a/tests/functional_tests.py
+++ b/tests/functional_tests.py
@@ -10,15 +10,24 @@ def test_page_that_exists(client):
 
 
 def test_page_that_doesnt_exist(client):
-    """Test that the app returns 404 for nonsense requests."""
+    """Test that the app returns 404 for nonsense requests and they use my error page."""
     response = client.get('/ohuesthaoeusth')
     assert response.status_code == 404
+    assert b'<b><tt>/ohuesthaoeusth</tt></b> does not seem to exist' in response.data
 
 
 def test_files_outside_pages_do_not_get_served(client):
-    """Test that page pathing doesn't break out of the instance/pages/ dir."""
+    """Test that page pathing doesn't break out of the instance/pages/ dir, and the error uses my error page."""
     response = client.get('/../unreachable')
     assert response.status_code == 400
+    assert b'You\'re doing something you\'re not supposed to. Stop it?' in response.data
+
+
+def test_internal_server_error_serves_error_page(client):
+    """Test that various exceptions serve up the 500 page."""
+    response = client.get('/actually-a-png')
+    assert response.status_code == 500
+    assert b'INTERNAL SERVER ERROR' in response.data
 
 
 def test_weird_paths_do_not_get_served(client):
diff --git a/tests/instance/pages/actually-a-png.md b/tests/instance/pages/actually-a-png.md
new file mode 100644
index 0000000..c592d25
Binary files /dev/null and b/tests/instance/pages/actually-a-png.md differ