While there is evidence, that mental health and substance abuse disorders have a co-occurrence rate of at least 50%, people are rarely treated for both disorders. Assuming that structural barriers prevent access to treatment, SAMHSA began a program of Co-occurring State Incentive Grants (COSIG) in 2003. We faced several problems in designing a national evaluation to assess structural changes states pursued, how they organized create change, and the sustainability of changes. The evaluation began two years after the program, states selected goals from different domains, state environments varied, and states received different funding levels. We undertook repeated interviews with key informants through site visits and extensive review of project documentation, as well as special studies. Among the findings, screening, workforce development, and services integration were goals that most states pursued showing sustainable change, but the 15 states varied widely in the number and success of their change efforts.