Public Participation in Scientific Research (PPSR) refers to intentional research collaborations between professional scientists and members of the public, where the initiative aims to build on established knowledge and to contribute new understandings. PPSR efforts have emerged from a variety of social and academic traditions ranging from participatory action research in the fields of development studies and public health, to citizen science projects with a long history in ornithology and astronomy research, to water quality monitoring and community-based natural resource management. In contexts of conservation and ecology, such efforts invariably confront the complexity of questions and issues related to people in their environments. As such, there are demands for PPSR initiatives in these contexts to meet complex and often multiple goals, generally for multiple constituents. Across the range of PPSR projects operating in conservation contexts, project goals and outcomes tend to fall into three main categories: those for research (e.g., scientific findings), for individual participants (e.g., access to information or acquiring new skills), and/or for socio-ecological systems (e.g., influencing policies, improving communities, and/or taking conservation action). Until recently, little in the way of empirical data has been available to inform design choices regarding what types of approaches yield what outcomes, and thus it can be difficult for project leaders and collaborators to make strategic decisions about aligning goals, outcomes, and tradeoffs in the design and refinement of projects. We discuss how recent work in multiple traditions converges to describe three different models of public participation in scientific research (PPSR), all suggesting that the degree to which the public participates in a given scientific research endeavor is a key predictor of project outcomes. These intentional collaborations can also be understood as operating within a common logic framework, which acknowledges the multiple, integrated goals of such projects and considers how the degree and quality of participation relates to specific outcomes. Designers and facilitators of initiatives involving public participants in scientific research can use the framework and models to reflect on relationships between their approaches to collaboration with public audiences and observed outcomes, and may consider how applying ideas from other approaches could more intentionally target their goals.