This case study examined the functional role activities of developmental evaluators in a school and community partnership employing a collaborative program model to improve an urban underperforming public school. Program implementers' assessments of program developments and their experience with developmental evaluators were also examined. Data sources included program documents, evaluator field notes, and two rounds of interviews with program implementers. Findings indicate that evaluators responded to emergent needs with intervention activities, which involved diagnosing program conditions and focusing on two evaluative targets, the program in context and implementers' evolving understanding of cross-agency collaboration. Evaluators' influence was greatest in relation to their direct facilitation of the project team and neutrality was a valued evaluator quality. Further research exploring evaluator direct and indirect influence on implementer learning is needed to advance developmental evaluation theory and the concept of program developments.