Health promotion views collaborations between local governments and citizens as key to improving health and lessening inequities in urban areas. Public parks, which are typically managed by local governments, are key settings for promoting physical activity, positive social interactions and overall well-being. Yet research on civic participation in park management is essentially absent from the health promotion literature. When the City of Calgary began to implement a new policy on off-leash dogs in parks, we had an opportunity to study civic participation in decision-making. We did so by examining policy documents, participating in meetings and conducting interviews. Off-leash parks have particular relevance for health promotion because they may support physical activity and networking for some, but may escalate conflict and deter park use amongst others. In this case study, the local government engaged citizens in developing an overarching off-leash policy for the city as a whole and in implementing the new policy at the level of neighbourhoods. Of the first three parks to be considered under the new policy, an off-leash area was ultimately designated in just one: a park located in a disadvantaged neighbourhood. By exploring this unexpected outcome, our case study suggests that public engagement, as practiced by local policymakers, may differ from community participation, as endorsed in health promotion. Further reflection on the meaning of ‘public’ is warranted in public health.