Background: Connectedness to school is a significant predictor of adolescent health and academic outcomes. While individual predictors of connectedness have been well-described, little is known about school-level factors which may influence connectedness. A school's ecology, or its structural, functional, and built aspects, coupled with interpersonal interactions, may also help to enhance adolescent connectedness. Aim: This study aims to identify school ecological characteristics which predict enhanced connectedness in secondary school. Sample: Data from 5,159 Grade 8 students (12-13 years) from 39 randomly selected schools were tracked until the end of Grade 9 (13-14 years). Method: Students' self-reported school, teacher, and family connectedness, mental health and peer relationships were measured at two time points. Accounting for school-level clustering, student- and school-level ecological characteristics were modelled on self-reported school connectedness in Grades 8 and 9. Results: Students' higher school connectedness in Grades 8 and 9 was influenced by greater levels of family connectedness, fewer classroom and peer problems, less difficult secondary school transition, fewer emotional problems, and greater prosocial skills. Seven school-level ecological variables were significantly associated with school connectedness after controlling for student-level predictors. At the school-level, priority for pastoral care and students' aggregated writing skills scores significantly predicted concurrent and future enhanced connectedness. Conclusions: Interventions to improve students' school connectedness should address individual student characteristics "and" school functional features such as pastoral care strategies and helping students to achieve greater academic outcomes. Future studies should focus on the cumulative longitudinal influence of school ecological and student-level predictors of school connectedness.