IntroductionWith obesity rates rising in Canada, schools have been identified as an ideal setting for health promotion interventions. In 2011, Ontario's School Food and Beverage Policy (P/PM 150) was mandated by the Ministry of Education for all schools in the province to try and improve the diets and food behaviours of youth. Policies have been introduced in a number of jurisdictions internationally, but what is not known are the best ways to implement them.PurposeThe purpose of this research was to i) describe the school food context in one Ontario Region, ii) examine, from the perspectives of multiple stakeholders, the process of P/PM 150 implementation including perceived challenges/successes with policy implementation and its impacts; iii) analyze the results in relation to the constructs of Damschroder's Consolidated Framework for Implementation Research (CFIR).MethodsA qualitative interpretive study was conducted to capture perceptions of stakeholders (students, parents, school stakeholders and food service providers) in one large, diverse region in Ontario, Canada. This qualitative study consisted of 5 food service provider interviews, 15 school stakeholder interviews, 5 elementary school parent focus groups, and 11 student focus groups. Two surveys were conducted that provided responses to open‐ended questions from 46 secondary school parent surveys, and 1,251 Grade 6–10 students. Focus group and open ended survey data were analyzed using NVivo 10 qualitative analysis software.ResultsResults reported on stakeholder perceptions of: i) school food, ii) school food behaviours, iii) factors that influence school food behaviours (including individual, social, macro‐level factors), iv) and the multiple environments (school, home, community) that influence food behaviours. Policy‐specific results provided stakeholders’ knowledge and opinions of P/PM 150, the process of policy implementation, factors influencing policy implementation (including successes and challenges) as well as the perceived outcomes and impacts of the policy on school food environments and student food behaviours. All results were analyzed using Damschroder's CFIR to better understand how the domains and constructs described in the framework related to school food policy implementation in this Region. Factors influencing policy implementation will be presented. These closely aligned with the constructs described in CFIR. Two additional constructs were identified that were not reflected in the framework: ‘implementation climate outside the school’ and ‘adaptability of the inner setting’. Study results indicated that these were significant factors influencing implementation in Peel Region schools. Therefore, these factors should be a considered in further revisions of the framework, in particular where it is being used to support policy implementation.ConclusionImplementation of a new school food policy, P/PM 150, was found to be complex with many factors influencing its successful uptake by school stakeholders. While participants discussed many challenges and negative outcomes and impacts resulting from P/PM 150, positive impacts on school food and food behaviours were also reported. Those planning to implement school food policies in the future need to consider comprehensive approaches that address potential influencing factors and environments outside of the school that impact student food behaviours.Support or Funding InformationFunding: CIHR‐Danone Institute Doctoral Research Award & Peel Public Health