In recognition of the growing challenge that food insecurity has on population health, a multisectoral partnership in Nova Scotia has been working since 2001 to address province-wide accessibility to a nutritious diet. The participatory food costing (PFC) model has been at the forefront of provincial and national efforts to address food insecurity; a local foods component was incorporated in 2004. This model has engaged community partners, including those affected by food insecurity, in all stages of the research, thereby building capacity at multiple levels to influence policy change and food systems redesign. By putting principles of participatory action research into practice, dietitians have contributed their technical, research, and facilitation expertise to support capacity building among the partners. The PFC model has provided people experiencing food insecurity with a mechanism for sharing their voices. By valuing different ways of knowing, the model has facilitated much-needed dialogue on the broad and interrelated determinants of food security and mobilized knowledge that reflects these perspectives. The development of the model is described, as are lessons learned from a decade of highly productive research and knowledge mobilization that have increased stakeholders' understanding of and involvement in addressing the many facets of food security in Nova Scotia.