Abstract
The objective of the paper is to study how 15 year old students' perceptions of the psychosocial environment in their schools, defined as student autonomy, teacher support, student support and demands, relate to smoking and alcohol use. Data from 15 year old students in Finland and Norway are included (n=2.816), using structural equation modelling to test theoretical models. The best model fitting the data shows that low student autonomy, low teacher support, student support and inadequate demands are significantly associated with health compromising behaviours directly, and indirectly through students' satisfaction with school. Low student autonomy is the strongest predictor of the four. The suggested relationships stress the need to develop and implement strategies to improve students' perceived school environment, and in particular students' autonomy, as a means of reducing the onset and continuance of health compromising behaviours in adolescents.