Knowing how people think about public participation processes and knowing what people want from these processes is essential to crafting a legitimate and effective process and delivering a program that is widely viewed as meaningful and successful. This article reports on research to investigate the nature of diversity among participants' perceptions of what is the most appropriate public participation process for environmental assessment and decision making in 10 different cases. Results show that there are clearly distinct perspectives on what an appropriate public participation process should be. We identified four perspectives: Science-Centered Stakeholder Consultation, Egalitarian Deliberation, Efficient Cooperation, and Informed Collaboration. The literature on public participation tends to presume that there are clear and universal criteria on how to “do” public participation correctly or that context is the critical factor. This study has revealed that even within a specific assessment or decision-making effort, there may be different perspectives about what is viewed as appropriate, which poses a challenge for both theorists and practitioners. Among the active participants in these 10 case studies, we found limited agreement and strong differences of opinions for what is a good process. Points of consensus across these cases are that good processes reach out to all stakeholders, share information openly and readily, engage people in meaningful interaction, and attempt to satisfy multiple interest positions. Differences appeared about how strongly to emphasize science and information, how much leadership and direction the process needs, what is the proper behavior of participants, how to tackle issues of power and trust, and what are the outcome-related goals of the process. These results challenge researchers and practitioners to consider the diversity of participant needs in addition to the broad context when conceptualizing or carrying out participatory processes.