Since psychology professionals have a moral and ethical responsibility to evaluate the effectiveness of different products and services aimed at improving psychological/physical well-being, development, and/or performance, the purpose of the present investigation was to evaluate the effectiveness of the Winners for Life book (and accompanying Parent Instructor Guide) on improving a variety of psychological factors for at-risk adolescents. Participants were 96 pairs from the Big Brothers/Little Brothers, Big Sisters/Little Sisters program. Participants were randomly assigned to one of three conditions: Winners for Life book, Winners for Life book plus instructor guide, or control group. Each group participated in a 12-week intervention program. Results revealed that both Winners for Life book conditions resulted in greater increases in self-esteem, self-perceived goal setting ability, optimism, and hope than the control condition, with the Winners for Life book plus instructor guide condition achieving the greatest improvements.