diff --git a/app/forms/__init__.py b/app/forms/__init__.py
index c98a5d5..7004f24 100644
--- a/app/forms/__init__.py
+++ b/app/forms/__init__.py
@@ -1,4 +1,4 @@
 # flake8: noqa F401
 from .auth import LoginForm
 from .user import UserForm, NewUserForm
-from .book import CreateBookForm
+from .book import CreateBookForm, AddContributorForm
diff --git a/app/forms/book.py b/app/forms/book.py
index fecb7b4..c9d5ec9 100644
--- a/app/forms/book.py
+++ b/app/forms/book.py
@@ -1,8 +1,23 @@
 from flask_wtf import FlaskForm
-from wtforms import StringField, SubmitField
+from wtforms import StringField, SubmitField, SelectField
 from wtforms.validators import DataRequired, Length
 
+from app import models as m
+
 
 class CreateBookForm(FlaskForm):
     label = StringField("Label", [DataRequired(), Length(6, 1024)])
     submit = SubmitField("Add new book")
+
+
+class AddContributorForm(FlaskForm):
+    user_id = StringField("User ID", [DataRequired()])
+    role = SelectField(
+        "Role",
+        choices=[
+            (member.value, name.capitalize())
+            for name, member in m.BookContributor.Roles.__members__.items()
+        ],
+    )
+
+    submit = SubmitField("Add Contributor")
diff --git a/app/views/book.py b/app/views/book.py
index 629c314..594d992 100644
--- a/app/views/book.py
+++ b/app/views/book.py
@@ -1,8 +1,7 @@
 from flask import Blueprint, render_template, flash, redirect, url_for
-from flask_login import login_required
+from flask_login import login_required, current_user
 
-from app import models as m
-from app import forms as f
+from app import models as m, db, forms as f
 from app.logger import log
 
 bp = Blueprint("book", __name__, url_prefix="/book")
@@ -49,3 +48,29 @@ def create():
             for error in errors:
                 flash(error.replace("Field", field_label), "danger")
         return redirect(url_for("book.get_all"))
+
+
+@bp.route("/<int:book_id>/add_contributor", methods=["POST"])
+@login_required
+def add_contributor(book_id):
+    # TODO replace redirects to book.edit/settings
+    book: m.Book = db.session.get(m.Book, book_id)
+    if book.owner != current_user:
+        flash("You are not owner of this book!", "danger")
+        return redirect(url_for("book.get_all"))
+
+    form = f.AddContributorForm()
+
+    if form.validate_on_submit():
+        role = m.BookContributor.Roles(int(form.role.data))
+        m.BookContributor(user_id=form.user_id.data, book_id=book_id, role=role).save()
+
+        flash("Contributor was added!", "success")
+        return redirect(url_for("book.get_all"))
+    else:
+        log(log.ERROR, "Book create errors: [%s]", form.errors)
+        for field, errors in form.errors.items():
+            field_label = form._fields[field].label.text
+            for error in errors:
+                flash(error.replace("Field", field_label), "danger")
+        return redirect(url_for("book.get_all"))
diff --git a/tests/test_book.py b/tests/test_book.py
index 94b8355..3ddef7c 100644
--- a/tests/test_book.py
+++ b/tests/test_book.py
@@ -62,21 +62,51 @@ def test_create_book(client: FlaskClient):
     assert len(book.versions) == 1
 
 
-# def test_add_c(client: FlaskClient):
-#     login(client)
+def test_add_contributor(client: FlaskClient):
+    _, user = login(client)
+    user: m.User
 
+    moderator = m.User(username="Moderator", password="test").save()
 
-#     response: Response = client.post(
-#         "/book/create",
-#         data=dict(
-#             label=BOOK_NAME,
-#         ),
-#         follow_redirects=True,
-#     )
+    moderators_book = m.Book(label="Test Book", user_id=moderator.id).save()
+    response: Response = client.post(
+        f"/book/{moderators_book.id}/add_contributor",
+        data=dict(user_id=moderator.id, role=m.BookContributor.Roles.MODERATOR),
+        follow_redirects=True,
+    )
 
-#     assert response.status_code == 200
-#     assert b"Book added!" in response.data
+    assert response.status_code == 200
+    assert b"You are not owner of this book!" in response.data
 
-#     book = m.Book.query.filter_by(label=BOOK_NAME).first()
+    book = m.Book(label="Test Book", user_id=user.id).save()
 
-#     assert book
+    response: Response = client.post(
+        f"/book/{book.id}/add_contributor",
+        data=dict(user_id=moderator.id, role=m.BookContributor.Roles.MODERATOR),
+        follow_redirects=True,
+    )
+
+    assert response.status_code == 200
+    assert b"Contributor was added!" in response.data
+
+    contributor: m.BookContributor = m.BookContributor.query.filter_by(
+        user=moderator, book=book
+    ).first()
+    assert contributor.role == m.BookContributor.Roles.MODERATOR
+    assert len(book.contributors) == 1
+
+    editor = m.User(username="Editor", password="test").save()
+    response: Response = client.post(
+        f"/book/{book.id}/add_contributor",
+        data=dict(user_id=editor.id, role=m.BookContributor.Roles.EDITOR),
+        follow_redirects=True,
+    )
+
+    assert response.status_code == 200
+    assert b"Contributor was added!" in response.data
+
+    contributor: m.BookContributor = m.BookContributor.query.filter_by(
+        user=editor, book=book
+    ).first()
+    assert contributor.role == m.BookContributor.Roles.EDITOR
+    assert len(book.contributors) == 2