This paper describes three national studies on factors relating to successful special education interdistrict cooperatives. Interdistrict cooperatives are formal organizations between state departments of education and school districts to share costs and resources in implementing programs for participating school districts. The first study provided descriptive data about the cooperatives and found that governance structure had no impact on the cooperatives' effectiveness. The second study investigated the contents of the governance guidelines and found that two characteristics were statistically significant: (1) state education agency approval of operational procedures prior to establishment; and (2) ability of cooperatives to function independently of state education agencies. The third study investigated the 16 states that reported having cooperatives that were self-governed by the member districts. Seventy percent of the 350 chairpersons of the cooperatives' governing boards responded to a survey. The findings suggest that managerial and organizational factors are more likely to distinguish between effective and ineffective cooperatives than governance or demographic factors. Breakdown of cooperatives by state and recommended operational guidelines are included in the tables. (LP)