Mobilizing Students to Improve School Meals, Boost Participation, and Prevent Obesity - One in five children and teens in the US has obesity, particularly impacting low-income youth. School meal programs serve ~30 million US children daily, playing an important role in improving nutrition and health. These meals must adhere to standards, offering healthier options than many meals from home or elsewhere. This is especially critical for students from lower-income backgrounds who have poorer dietary quality and higher obesity rates and blood pressure. Some states, like California provide free meals to all public-school students, but~ 20 million students still don’t participate. While some programs have successfully increased meal participation, high school students are usually not involved in creating solutions, despite their lower participation rates. The San Joaquin Valley (SJV) Child Nutrition Alliance is a community-academic partnership collaborating to improve healthy food access in the largely rural and low-income SJV region with high rates of diet-related diseases. The Alliance’s research found challenges to meal participation including lack of awareness about the program’s benefits, concerns about the quality of food served (e.g., high added sugar, processed items, lack of fresh produce), limited knowledge of schools’ challenges in providing healthy meals (e.g., limited kitchen space, staffing, budgets,) and a need for better collaboration with schools. School Meal Action will be implemented in high schools serving low-income students, who have poorer diet quality, to address these issues. The youth-led program will train students on: 1) the history, requirements, and logistics of school nutrition programs, 2) Photovoice method that uses photography and discussions to highlight challenges and solutions related to school nutrition, and 3) ways to work with their local school and school district to advance solutions identified from Photovoice. This study will evaluate School Meal Action in 24 SJV high schools serving low-income students. Half will be randomized to receive the intervention immediately; the other half will follow a financial literacy curriculum. After the study, control schools will be encouraged to independently implement School Meal Action with materials from the study team. All schools will receive evaluation at study start and again at 1- and 12-months post-intervention. A major goal is to assess the program’s impact on students’ BMI z-scores (weight/height measurements) and dietary quality (validated 24- hour diet recalls). The study will also examine changes in students’ knowledge, attitudes, skills, and selfconfidence (surveys) and blood pressure (measurements). At the school-level, researchers will assess changes in meal participation and nutrition guidelines and practices (High School Physical Activity & Nutrition Tool). This hybrid trial will utilize implementation frameworks to examine the program’s reach, effectiveness, and sustainability using the data described, along with school observations, and interviews/focus groups with student participants and program implementers. If successful, School Meal Action could offer a scalable solution to enhance nutrition and promote health for millions of US students.