The authors suggest that traditional evaluation approaches (formative and summative) fail to meet the complex needs of social sector innovators. Instead, grantmakers should approach evaluation differently, specifically involving the use of developmental evaluation (attributed to Michael Quinn Patton). Through a review of literature, interviews, and case studies, this piece assists with putting developmental evaluation into practice. At the heart of this call for new evaluation approaches, is the encouragement of social innovation and change. Stanford University’s Center for Social Innovation defines social innovation as, “a novel solution to a social problem that is more effective, efficient, sustainable, or just than present solutions and for which the value created accrues primarily to society as a whole rather than private individuals” (p. 2). Social innovations are often cross-sector, involve many stakeholders, and challenge conventional wisdom. Because of this complexity, the pathways to results and even the results are “unpredictable and emergent” (p. 3). These scenarios require strategic learning, including data collection and evaluation, to inform decision-making and strategy. The authors briefly review and compare development, formative, and summative evaluation approaches and accompanying scenarios for appropriate application. Developmental evaluation should be explored with initiatives that embark on experimentation, uncertainty, and inquiry. Five characteristics distinguish developmental evaluation from other types: “the focus of the evaluation, the intentionality of learning throughout the evaluation, the emergent and responsive nature of the evaluation design, the role and position of the evaluator, and the emphasis on using a systems lens for collecting and analyzing data, as well as for generating insights” (p. 7). Conditions for a Successful Developmental Evaluation Plan, including fit and readiness, are presented graphically and reviewed in-depth. The four conditions include: flexible leadership, organizational values, sufficient resources, and open and transparent communication. Case studies from the Bill & Melinda Gates Foundation (p. 9), the J.W. McConnell Family Foundation (p. 15), and the Knight Foundation (p. 17) serve as examples of real-world developmental evaluation efforts. The authors discuss common questions facing the developmental approach, including accountability, rigor, budget, and decision-making roles. The Foundation Strategy Group (FSG) is a nonprofit consulting firm specializing in strategy, evaluation, and research. See author Hallie Preskell’s blog post about this research with FSG.