There are thousands of watershed groups across the United States that are engaging in efforts to reduce nonpoint source pollution (NPS). Collaboration can be an effective means of achieving reduction in NPS, and factors that have been identified as contributing to successful collaborations include effective leadership, social capital, and social networks. These concepts are used as the overarching framework of this dissertation. First, a study is presented that examines the role of water quality relevant social capital in a structural equation model of behavior use and awareness. Drawing upon theories of behavior adoption, the final model proposes that awareness directly influences social capital and attitudes, which in turn directly affect behavior use and awareness. Data come from a mail survey of a Midwestern watershed population (n=338). Results indicate that social capital is a meaningful variable to include in such models, and that attitudes are not a significant variable. Second, social capital is examined qualitatively in a comparative case study of three Midwestern watershed groups. The findings identify meaningful outcomes related to the purposive formation of a watershed group, and how access to particular social network resources can aid in achieving group successes. One of the three watersheds was formed purposively for the greatest access to human capital and external social network ties. Data come from 37 interviews conducted over a two year period. The third study examines leadership issues in one Midwestern watershed group, and applies both traditional and collaborative leadership theories to discuss phenomena that emerged from 17 longitudinal qualitative interviews and meeting observations. Findings show that in this case, roles of committee members and paid staff need to be clarified for the group to regain its early momentum. Moreover, watershed groups receiving government funds that are housed at local agencies will benefit from clearly defining where decision making authority lies, with the agency or with the group