To provide a rationale for working with families of clients with psychiatric and substance use disorder, and to describe a new program, family intervention for dual disorders (FIDD).We developed and manualized the FIDD program, which includes both single-family and multiple-family group formats. We trained several clinicians at a local mental health center in the model and conducted a small pilot study.Clinicians were able to implement the program, and to successfully engage families in treatment. Most clients demonstrated significant improvements in substance abuse over one to two years of treatment.The FIDD program is feasible and appears to promote collaboration between families and professionals, thereby improving the course of dual disorders. Controlled research is underway to evaluate the effects of the FIDD program on client and family outcomes.