question: BACKGROUND: Pediatric obesity is one of the most important health challenges of the twenty-first century. Primary prevention of childhood obesity, can lessen its consequences. This study aims to assess childhood obesity prevention policies in Iran through a policy analysis of agenda-setting using Kingdon’s multiple streams. METHODS: A qualitative study was conducted using in-depth interviews with 39 key informants and document review from different stages of the policymaking process of childhood and adolescent obesity prevention programs in Iran. The analysis of documents and interviews were guided based on Kingdon’s multiple streams (problem, policy and political streams). RESULTS: The important factors of the problem stream were the high prevalence of childhood and adolescent obesity and its risk factors in Iran. In the policy stream, a focus on preventing non-communicable diseases in the health system, increasing the workforce in health centers, promoting health school programs, and creating healthy eating buffets in schools was identified. Under the political stream, the impact of the WHO ECHO program in 2015 and the implementation of the health system transformation plan in Iran in the new government took place after 2013, caused the Iran ECHO program entered the agenda and implemented from 2016. CONCLUSIONS: Now that a window of opportunity for childhood and adolescent obesity prevention policymaking has been created, the problems such as the therapeutic approach in the health system, the existence of sanctions against Iran and outbreak of coronavirus disease-19 (COVID-19), have hindered the successful implementation of this policy and the opportunity window has not been well used. However, actors need political support from the high levels of government to keep this policy on the agenda.