BackgroundOnly three of twenty Caribbean Community (CARCICOM) countries have mandatory school nutrition policies despite one third of the region’s children being overweight or obese. In Barbados, there are nutrition guidelines which lack the legal mandate of a formal policy. We aim to assess the comprehensiveness of current national nutrition guidelines and to understand the factors operating in the inner and outer school setting that may influence the implementation of a mandatory school nutrition policy from the perspectives of school administrators.MethodsA documentary analysis of existing nutritional guidelines was conducted along with qualitative semi-structured interviews in primary (elementary) and secondary (high) schools in Barbados. We purposively sampled six primary and four secondary school administrators (principals, deputy principals or senior teachers) to explore their knowledge and views on the National School Nutrition Guidelines. The deterministic implementation paradigm, Consolidated Framework for Implementation (CFIR), was used to explore the complexities within the inner and outer settings of schools. Documentary analysis used a theory-based framework informed by the Wellness School Assessment Tool—school policy analysis questionnaire. Interview transcripts were team coded using thematic analysis with constant comparison facilitated by NVIVO software version12.ResultsSchool administrators were unaware of the existing National School Nutrition Guidelines which documentary analysis found to be restrictive and weak for implementation. Administrators envisioned a government-led (outer setting), whole of society approach as the most effective strategy for the development and implementation of a proposed mandatory school nutrition policy. School administrators identified lack of financial and human resources as barriers to nutrition policy implementation. Formal and informal food vendors are institutionalized in schools and are influential determinants of the school food environment. Schools have individually reached into the outer setting to work with civil society organizations and private individuals to provide financial support and nutrition expertise to their institutions. Mass media campaigns in the outer setting may influence child and parental food choices.ConclusionSchool administrators describe that government-led, CSO supported policy development using a whole-of-society approach has implications for improving nutrition policy implementation. Our findings demonstrate the use of a deterministic implementation framework in the pre-implementation phase of school nutrition policy development.