This article examines New Haven (Connecticut) Public Schools' efforts to create a new teacher evaluation model in a collaborative manner. Based on semistructured interviews with nearly 100 educators, we develop a case study charting the progress of the new system, TEVAL, from an initial concept through early implementation. We find that John Kingdon's three streams--problems, politics, and policies--all aligned in the years preceding TEVAL's adoption and were supported by local policy entrepreneurs. Notably, we also find that TEVAL's progress was further facilitated by the relationships and interactions among the participants themselves.