The Montana Youth Risk Behavior Survey (YRBS) is administered by the Montana Office of Public Instruction every two years to students in grades 7 through 12. The purpose of the survey is to help monitor the prevalence of behaviors that not only influence youth health, but also put youth at risk for the most significant health and social problems that can occur during adolescence. The 2021 YRBS was conducted in February-March 2021. Data used in this report from the 2021 YRBS are based on a random sample survey of Montana high school students. The weighted data results contained in this report can be used to make inferences about the priority health-risk behaviors of all high school students in grades 9 through 12 in all schools in Montana. For the purpose of this report, two responses from the "breakfast" question were compared with association to other health risk behaviors: students who reported that they did not eat breakfast on any of the past 7 days and students who reported eating breakfast on all of the past 7 days. Fifty-four separate risk behaviors were queried for association with eating or not eating breakfast. These findings are presented in bullet, table, and graph forms in the report. [This report was produced by the Montana Office of Public Instruction's Coordinated School Health Unit. For the 2019 report, see ED599095.]