How many books are in the 'Twilight' saga?

The saga contains four books: Twilight, New Moon, Eclipse and Breaking Dawn.

There is also a shorter novel about one of the minor characters in the series: The Short Second Life of Bree Tanner.

Meyer did begin to write another book with the story of Twilight from Edwards' perspective, but the project was halted after several chapters were leaked online. It will probably remain unfinished.