Supportive and caring relations within families promote academic achievement and protect against involvement in health-risk behaviors by adolescents. Similarly, supportive and caring relationships within schools (henceforth, school connectedness) promote academic motivation among adolescents. Much less is known, however, about the influence of school connectedness on adolescent health-risk behaviors. Previous research generally suffers from two limitations. First, most research is cross-sectional. The longitudinal research that does exist does not distinguish between initiation or escalation or reduction of health-risk behaviors. Second, school connectedness has generally been treated as a broad construct that combines students' perceptions of safety, support, belonging and engagement. Such a broad conceptualization does not provide clear guidance to policy makers and practitioners on how to increase school connectedness. This paper addresses these limitations by exploring the association between two dimensions of school connectedness--perceived teacher support and social belonging--and the initiation, escalation and reduction of participation in six adolescent health-risk behaviors. (Contains 5 tables.)