This is the dataset used in analysis of the temporal relationship between of alcohol related attitudes and heavy episodic drinking in adolescents. These data are an excerpt from the Steps Towards Alcohol Misuse Prevention Programme (STAMPP) study, a school- and community-based cluster randomised controlled trial. The overall aim of the trial (from which these data were extracted) was to assess the effectiveness and cost-effectiveness of a combined classroom curriculum and parental intervention on self-reported alcohol use [heavy episodic drinking (HED)] and alcohol-related harms (indicators such as getting into fights after drinking, poorer school performance and trouble with friends and family) amongst teenage pupils. The trail was a two-arm, cluster randomised controlled trial with schools as the unit of randomisation. A total of 105 post-primary schools in Northern Ireland (NI) and Glasgow/Inverclyde Educational Authority areas participated. A total of 12,738 male and female secondary school students (intervention delivered when students were in school year 9 in NI or S2 in Scotland in the academic year 2012–13 and aged 12–13 years) were randomised. Randomisation and baseline (T0) surveys took place when children were in school year 8 or S1. Schools were randomised (1:1) by an independent statistician to the Steps Towards Alcohol Misuse Prevention Programme (STAMPP) or to education as normal (EAN). All schools were stratified by free school meal provision. Schools in NI were also stratified by school type (male/female/coeducational). The study used two primary outcomes, a) self-reported HED (defined as self-reported consumption of ≥ 6 units in a single episode in the previous 30 days for male students and ≥ 4.5 units for female students) assessed at 33 months from baseline (T3); and b) the number of self-reported harms (harms caused by own drinking) assessed at T3. The full NIHR report can be found at https://dx.doi.org/10.3310/phr05020. The dataset presented here were used in secondary analysis of the alcohol-related attitude questions and are therefore a subset of the full data set. The data are presented in a tab delimited [.dat] file as the analysis was undertaken in Mplus. It is also available as a CSV. Full details of the Mplus code used in the analysis can be found at https://osf.io/bmhak/?view_only=67d2dc1013af46a880662a2c8067635
