Although collaboration is recognized as an effective means to address multifaceted community issues, successful collaboration is difficult to achieve and failure is prevalent. To effectively collaborate, collaborators must recognize the strengths and weaknesses within their own efforts. Using Mattessich and colleagues' work as a springboard, a seven-factor model of effective collaboration is presented along with an accompanying evaluation tool, the Collaboration Assessment Tool (CAT). Confirmatory factor analysis of the CAT validated the proposed model with all seven collaboration factors demonstrating strong internal consistency. Concurrent validity was established through expected positive intercorrelations between the factors as well as strong positive correlations with the perceived success of collaborative efforts. As evaluators are increasingly asked to evaluate collaborations and coalitions, this conceptual model and tool can provide evaluators with a grounded, reliable, and valid assessment instrument to work with clients to build collaborative efforts in an intentional, comprehensive, and effective manner.