This Study was done in an effort to engage Clinical Psychologist to take the lead in conducting vigorous, robust research work on the application of positive psychology in Nigeria clinical settings. The three domains of conceptual framework in positive psychology are (1) the Pleasant Life, (2) the Engaged Life and (3) the Meaningful Life. This study examined the treatment effect of Positive Psychotherapy and Cognitive Behavioural therapy in treating depression in individuals with co-occurring (Co-morbidity) depression and substance dependence.