The Central Texas Coordinated Approach To Child Health (CATCH) Middle School Project is a 3.5-year school-based project aimed at promoting physical activity (PA), healthy eating, and obesity prevention among public middle school students in Texas. This article describes the CATCH intervention model and presents baseline findings from spring 2009. CATCH comprises six core components: CATCH Team, CATCH PE, CATCH Classroom, CATCH Eat Smart Cafeteria, CATCH Family, and CATCH Social Marketing. A group randomized serial cross-sectional design is being employed to test the effect of three program support conditions (n = 10 schools each) on energy-balance behaviors: Basic (training and curriculum only), Basic Plus (training and curriculum plus CATCH facilitator support), and Basic Plus Social Marketing (all inputs plus social marketing component). The study sample is composed of a cross-sectional sample of eighth-grade students (primary outcome evaluation sample) and sixth- and seventh-grade students (PE process evaluation sample) who are selected and measured each year. At baseline, 37.9% of eight-grade students (n = 2,841; 13.9 years) were overweight/obese and 19.2% were obese. Eighth-grade students reported, on average, consuming sugar-sweetened beverages more than two times on the previous day and fruits and vegetables roughly three times on the previous day; only two of five school districts surpassed the recommended 50% cut-point for class time spent in moderate-and-vigorous PA as measured in classes of sixth- and seventh-grade students. Additional behavioral findings are reported. Body mass index and behaviors were comparable across conditions. Baseline findings underscore the need to promote student energy-balance behaviors.