- Psychometric properties of the Dual-Disorder Treatment Fidelity Scale (Mueser et al. Integrated treatment for dual disorders: A guide to effective practice, 2003) were evaluated. Reliability was assessed through measures of inter-rater agreement, and validity was assessed through a concurrent known groups validation procedure. Two raters assessed three community mental health center (CMHC) and three specialized dual diagnosis (DDE) programs for fidelity; inter-rater agreement was good. Total fidelity scores did not distinguish between CMHC and DDE program types; however, a cluster analysis revealed concurrent validity based on the item level ratings. Conclusions drawn from item level ratings appear valid; the validity of conclusions based on total scores remains unsupported.