Participatory integrated assessment (PIA) emerged as a response to conventional integrated assessment methods in the mid-to-late 1990s. PIA is based on the tenet that more inclusive stakeholder involvement may lead to increased accountability and legitimacy in decision-making, greater levels of trust and social learning between participants, and improved quality and relevancy of knowledge outputs. In this paper, we conduct a systematic literature review to update and deepen our understanding of the approaches, methods, opportunities, and challenges associated with PIA as applied at the catchment scale. Of the total 278 studies identified in our literature search, only 37 catchment-level cases presented a clear PIA application. From our review, lessons learnt were drawn in relation to the integration of less-easily quantified areas of social science, entry and exit planning in PIA, boundary work on issue cycles and accounting for the human dimension. We conclude that PIA is a potentially useful approach for navigating the dual social-ecological dimensions of current environmental and resource management issues, especially when projects include tailored objectives and methods, user-friendly outputs, and early and consistent stakeholder involvement. However, we also highlight gaps in the field concerning the integrative reach of PIA, PIA's real-world impact, and the relationship between PIA processes and outcomes along stages of environmental issue cycles. We conclude that further work is therefore still needed to help advance the field of PIA in both research and boundary work practice.