Local governmental units in the United States are struggling to cope with dwindling public resources and surging public demands. They often turn to interlocal agreements (ILAs) as a collaborative means by which to more effectively serve their constituents. Unfortunately, many ILAs never materialize or fail prematurely. The purpose of this qualitative, phenomenological study was to explore the experiences of 13 purposefully selected mayors in the State of Indiana to discover what factors they considered important when making their ILA entry and continuation decisions. It utilized a conceptual framework based on the transaction costs theory, as informed by the utility maximization, bounded rationality, social decision scheme, and groupthink theories. Interviews were transcribed, and data were subjected to an inductive analysis using idiographic interpretation to develop themes and to describe the essence of the ILA decision-making process. Key findings included that direct cost savings, a detailed, written agreement, contractual flexibility, an ability to perform, the effect on constituents and the current municipal workforce, and having a trusted, like-minded partner were important ILA entry factors. Furthermore, contractual flexibility, meeting constituent expectations, service effectiveness, relevancy, having a communicative partner, being able to measure an ILA service, and saving money were important ILA continuation factors, but that both service quality and doing the right thing trumped saving money. These findings have implications for positive social change because they can assist local leaders in achieving ILA success, with society benefitting from a commensurate increase in public value and in the more efficient and effective meeting of societal needs.