This college textbook — written for the advanced undergraduate or graduate student in counseling, clinical psychology,and social work — is Albert Ellis’ final work. It thoroughly explains all the major personality theories from a historical perspective and in the light of recent research. This is the first textbook to formally present the REBT system of personality as taught by Dr. Ellis, whose insights are drawn from his own half-century of experience as a psychotherapist, as well as his intimate knowledge of the iconic figures who, along with Dr. Ellis, helped develop clinical psychology.