Evidence for effectiveness of school-based studies for prevention of adolescent obesity is equivocal. Tailoring interventions to specific settings is considered necessary for effectiveness and sustainability. The PRECEDE framework provides a formative research approach for comprehensive understanding of school environments and identification of key issues/areas to focus resources and energies. No reported studies have tested applicability of the PRECEDE framework in schools in relation to obesity. Adolescents (n = 362), parents (n = 349) and teachers (n = 146) from six secondary schools participated in two quantitative studies and two qualitative studies. Data collected from these studies permitted confirmation of adolescent overweight/obesity a health issue for schools; the need for secondary schools to focus health promotion efforts on healthy nutrition, with inclusion of parents/homes and appreciation for gender differences in developing interventions. Community buy-in and commitment to school-based obesity prevention programs may be dependent on initially addressing what may be perceived as minor issues, and developing policies to guide practices within schools in relation to supply and access to healthy foods, use of sporting equipment and participation in physical activities. The PRECEDE framework allows systematic assessment of school environments and provided opportunity to identify realistic and relevant interventions for promoting healthy adolescent physical activity and nutrition behaviors.