The sample comprised participants from the ALSPAC (http://www.alspac.bris.ac.uk; Golding et al., 2001). ALSPAC is an ongoing population-based study investigating a wide range of environmental and other influences on the health and development of children. All pregnant women resident in the Avon district of South West England with an expected date of delivery between April 1, 1991, and December 31, 1992, were invited to participate in the ALSPAC. The achieved sample was 14,541 pregnant women (80% of those eligible) with 13,988 live infants at age 12 months. ALSPAC parents and children have been followed up regularly since recruitment, with data obtained through questionnaires completed by mothers, children, and teachers and through clinical assessments. The present analyses used data collected at months 6, 24, 38, 42, 57, and 69 (on early childhood temperament), friendship characteristics collected at age 10.5 years, and personality characteristics collected at ages 11.5 and 13 years. Alcohol use outcomes were assessed at age 15.5. The number of individuals with data for each of the above measures analyzed in this project is shown in Table 1. There were 12,647
