Lesli Blair has been interested in both psychology and criminal justice her whole life. When she found her love for teaching while earning her doctoral degree, one of the first courses she taught was called The Psychology of Criminal Behavior. She honed this course over 10 years, never finding a textbook that fully met the needs of the course. Every existing textbook needed to be supplemented with other readings. Eventually, she realized that she needed to write this textbook. Hopefully, it will allow others to learn some of the many ways that psychology can help us understand crime and the criminal justice system.