Addictions undermine the quality of life of individuals and their families. They generally lead to misadjustment that affects many areas (psychological, family, social, and occupational) and, in the most severe cases, can end in helplessness, loneliness, or early death. The self-esteem of the person with addictions tends to be reduced and this limits their chances of recovery. Through this research, we tried to test the effect of a self-esteem workshop on 58 people with addictions to different substances. A self-esteem workshop was carried out with people who were part of a therapeutic community belonging to the province of Pontevedra (Spain). Several working groups were established and received sessions over a period of two and a half months. Participation was voluntary and the anonymity and confidentiality of the participants were guaranteed. To assess self-esteem, the Coopersmith Self-Esteem Scale Short Form, or Form B, was used at the beginning and at the end of the workshop. The results confirm the existence of statistically significant differences in the Self-Esteem Scale in relation to the pre-treatment and post-treatment assessments: F(1) = 106.44, p = 0.000, η2 = 0.655. The self-esteem workshop resulted in a significant change in this construct and contributed to the psychological improvement of people with addictions.