Introduction to Psychology
This is a free, online textbook from Saylor Foundation.
"Charles Stangor's Introduction to Psychology utilizes the dual theme of behavior and empiricism to make psychology relevant to intro students. Charles wrote this book to help students organize their thinking about psychology at a conceptual level. Five or ten years from now, he does not expect his students to remember the details of most of what he teaches them. However, he does hope that they will remember that psychology matters because it helps us understand behavior and that our knowledge of psychology is based on empirical study."