The most challenging aspect of writing a text is selecting what to include and what to omit. My primary goal in writing this text through each edition has been to show the importance of neuroscience, genetics, and evolution for psychology and not just biology. I have focused on biological mechanisms of such topics as language, learning, sexual behavior, anxiety, aggression, consciousness, attention, abnormal behavior, and the mind body relationship. I hope that by the end of the book readers will clearly see what the study of the brain has to do with “ real psychology” and that they will be interested in learning more. Each chapter is divided into modules; each module begins with its own introduction and finishes with its own summary this organization makes it easy for instructors to assign part of a chapter per day instead of a whole chapter per week.