Psychotherapists risk making 2 types of errors with clients who struggle with addictive behaviors: failure to diagnose addictive behaviors and failure to effectively treat addictive behaviors. Given the high prevalence of addictive behaviors in clinical populations, therapists are in a unique position to assist individuals with these problems. It is assumed that therapists possess general diagnostic and treatment skills and yet many do not diagnose or do not treat addictive behaviors. Reasons for making these errors include prohibitive beliefs and limited knowledge about addictive behaviors. We offer specific recommendations to reduce these psychotherapy errors. These include: (a) more deliberate screening and diagnosis of addictive behaviors, (b) increased application of empirically supported addiction treatments, (c) required education and training in addictive behaviors, (d) modification of prohibitive attitudes about addressing addictive behaviors, and (e) increased attention paid to the addictive behaviors by professional psychotherapy organizations.