Human service programs can be seen as proceeding through a number of stages in the course of their development. Each stage can be characterized by a major issue or question to be answered. Evaluation research, if appropriately matched to a program's stage of development, can help inform the decision making that goes on at each step and resolve the questions that need to be answered before proceeding to subsequent stages. This article presents a brief overview of what these stages are, the questions to be answered at each stage, and the kinds of research activity that can assist in answering those questions.