There are currently four books in the twilight saga; Twilight, New Moon, Eclipse, and Breaking Dawn. There is also a novella by Stephine Meyer from one of the minor characters in Eclipse. The novella is called "The Second Short Life of Bree Tanner". There is also an official guide written by the same author. It is called the Twilight Saga official guide. Those are all the books written and are currently published by the author of the series. THere are several other books based on the movies, but they were not included in the saga, as the only give information on the movies and not the books themselves.