Internationally, there is a growing call to embrace more participatory and democratic approaches to environmental science and policy to improve sustainability outcomes. This presents a particular challenge in Westminster-based systems of government, where participatory and inclusive structures for policy making are considered inherently difficult due, in part, to the high concentration of power in the executive and political elite. To better understand this challenge, we conducted exploratory research into the science–policy experiences of former environment ministers (politicians) and senior bureaucrats who have held executive roles in provincial/ state and federal governments across Canada and Australia and the national governments of New Zealand, Ireland, and the United Kingdom. Our results suggest that government organizations could further strengthen a culture of policy-relevant research and evidence-based policy on environment issues by fostering more decentralized approaches to policy and more democratic approaches to scientific knowledge production that better accounts for the complexity of environmental decision making.