diff --git a/amanuensis/backend/__init__.py b/amanuensis/backend/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/amanuensis/backend/user.py b/amanuensis/backend/user.py
new file mode 100644
index 0000000..9a28e67
--- /dev/null
+++ b/amanuensis/backend/user.py
@@ -0,0 +1,45 @@
+"""
+User query interface
+"""
+
+import re
+import uuid
+
+from amanuensis.db import DbContext, User
+from amanuensis.errors import ArgumentError
+
+
+def create_user(
+    db: DbContext,
+    username: str,
+    password: str,
+    display_name: str,
+    email: str,
+    is_site_admin: bool) -> User:
+    """
+    Create a new user.
+    """
+    # Verify username
+    if len(username) < 3 or len(username) > 32:
+        raise ArgumentError('Username must be between 3 and 32 characters')
+    if re.match(r'^[0-9-_]*$', username):
+        raise ArgumentError('Username must contain a letter')
+    if not re.match(r'^[A-Za-z0-9-_]*$', username):
+        raise ArgumentError('Username may only contain alphanumerics, dash, and underscore')
+    # Verify password
+    if not password:
+        raise ArgumentError('Password must be provided')
+    # If display name is not provided, use the username
+    if not display_name.strip():
+        display_name = username
+
+    new_user = User(
+        username=username,
+        password=password,
+        display_name=display_name,
+        email=email,
+        is_site_admin=is_site_admin,
+    )
+    db.session.add(new_user)
+    db.session.commit()
+    return new_user
diff --git a/amanuensis/errors.py b/amanuensis/errors.py
index 861d26b..dca7c6f 100644
--- a/amanuensis/errors.py
+++ b/amanuensis/errors.py
@@ -1,32 +1,10 @@
+"""
+Submodule of custom exception types
+"""
+
 class AmanuensisError(Exception):
-	"""Base class for exceptions in amanuensis"""
-
-
-class MissingConfigError(AmanuensisError):
-	"""A config file is missing that was expected to be present"""
-	def __init__(self, path):
-		super().__init__("A config file or directory was expected to "
-			f"exist, but could not be found: {path}")
-
-
-class ConfigAlreadyExistsError(AmanuensisError):
-	"""Attempted to create a config, but it already exists"""
-	def __init__(self, path):
-		super().__init__("Attempted to create a config, but it already "
-			f"exists: {path}")
-
-
-class MalformedConfigError(AmanuensisError):
-	"""A config file could not be read and parsed"""
-
-
-class ReadOnlyError(AmanuensisError):
-	"""A config was edited in readonly mode"""
+    """Base class for exceptions in amanuensis"""
 
 
 class ArgumentError(AmanuensisError):
-	"""An internal call was made with invalid arguments"""
-
-
-class IndexMismatchError(AmanuensisError):
-	"""An id was obtained from an index, but the object doesn't exist"""
+    """An internal call was made with invalid arguments"""
diff --git a/tests/test_db.py b/tests/test_db.py
index bd5d1a0..9e551b0 100644
--- a/tests/test_db.py
+++ b/tests/test_db.py
@@ -2,23 +2,47 @@ import pytest
 from sqlalchemy import func
 
 from amanuensis.db import *
+import amanuensis.backend.user as userq
+from amanuensis.errors import ArgumentError
 
 
 @pytest.fixture
-def session():
+def db():
     db = DbContext('sqlite:///:memory:', debug=True)
     db.create_all()
-    return db.session
+    return db
 
 
-def test_create(session):
+def test_create(db):
     """Simple test that the database creates fine from scratch."""
-    assert session.query(func.count(User.id)).scalar() == 0
-    assert session.query(func.count(Lexicon.id)).scalar() == 0
-    assert session.query(func.count(Membership.id)).scalar() == 0
-    assert session.query(func.count(Character.id)).scalar() == 0
-    assert session.query(func.count(Article.id)).scalar() == 0
-    assert session.query(func.count(ArticleIndex.id)).scalar() == 0
-    assert session.query(func.count(ArticleIndexRule.id)).scalar() == 0
-    assert session.query(func.count(ArticleContentRule.id)).scalar() == 0
-    assert session.query(func.count(Post.id)).scalar() == 0
+    assert db.session.query(func.count(User.id)).scalar() == 0
+    assert db.session.query(func.count(Lexicon.id)).scalar() == 0
+    assert db.session.query(func.count(Membership.id)).scalar() == 0
+    assert db.session.query(func.count(Character.id)).scalar() == 0
+    assert db.session.query(func.count(Article.id)).scalar() == 0
+    assert db.session.query(func.count(ArticleIndex.id)).scalar() == 0
+    assert db.session.query(func.count(ArticleIndexRule.id)).scalar() == 0
+    assert db.session.query(func.count(ArticleContentRule.id)).scalar() == 0
+    assert db.session.query(func.count(Post.id)).scalar() == 0
+
+
+def test_create_user(db):
+    """New user creation"""
+    kwargs = {
+        'username': 'username',
+        'password': 'password',
+        'display_name': 'User Name',
+        'email': 'user@example.com',
+        'is_site_admin': False
+    }
+
+    with pytest.raises(ArgumentError):
+        userq.create_user(db, **{**kwargs, 'username': 'user name'})
+
+    with pytest.raises(ArgumentError):
+        userq.create_user(db, **{**kwargs, 'password': None})
+
+    new_user = userq.create_user(db, **kwargs)
+    assert new_user
+    assert new_user.id is not None
+    assert new_user.created is not None