Background The importance of social determinants of adolescent health behaviour such as alcohol use has stimulated interest in family and school environments that may act as risk or protective factors. This study looked at characteristics of schools and parents, and how they influence young people’s alcohol use. Methods The Belfast Youth Development Study began in 2000. It surveyed secondary school children annually for five years of compulsory schooling, and two further years (age 16/17 & 21/22). This study is based on data from the first five data sweeps. We used the Stattin & Kerr parental monitoring measures, and alcohol use coded as: rarely/never, infrequently, monthly or less, weekly or more. Phase 1: Cross-lagged structural equation models assessed bi-directional associations between parental monitoring and subsequent alcohol use. Phase 2: Multilevel regression models assessed between-school variation in alcohol use frequency and the effect of parental monitoring. Phase 3: Structural equation models assessed the effect of parental attachment and parental monitoring, and how these two factors interacted to influence alcohol use. Results Analysis was based on 4,775 respondents attending 38 schools, the proportions drinking weekly or more frequently in each of the five years of the study were 4%, 11%, 21%, 27% and 34%. Phase 1: Parental monitoring was protective against frequent alcohol use (OR = 0.76, p < 0.01). More frequent alcohol use was also associated with lower parental monitoring to a lesser extent (b = -0.04 p < 0.05). Phase 2: Around 6% of the variation in alcohol use was attributable to differences between schools. The effect of parental monitoring on alcohol use varied widely between schools (OR 0.70 [95% coverage interval 0.52, 0.93]). Phase 3: Higher parental monitoring, and better parental attachment were protective against alcohol use. Better parental attachment was also associated with lower levels of parental monitoring; this meant better parental attachment was indirectly associated with higher frequency of drinking due to its effect to reduce monitoring. The combination of these two opposing influences led to parental attachment having zero overall influence on alcohol use. Conclusion School and home environment play an important role in shaping young people’s health risk behaviours. What these findings show is that the school environment may influence the extent to which parental behaviours can successfully reduce risk behaviour. While parent-child attachment may provide an important role for overall social functioning, improving monitoring behaviour may have a greater influence on alcohol use than improving attachment.