Results
During the first round a number of determinants of adolescent binge drinking were identified. For these determinants, the experts defined strategies to change that determinant in order to reduce binge drinking. These strategies, including the results of the second and third rounds, are listed in Table 2, Table 3, Table 4 and Table 5.
In the first round, 70 factors that determine binge drinking in adolescents, 40 strategies targeting parents, and 47 strategies targeting adolescents were identified. With regard to reducing drop-out, 17 and 19 strategies were identified for adolescents and parents, respectively. In the second round, experts reached consensus (IQD ≤ 1) on 16 strategy items that were considered important (Mdn ≥ 6). In the third round, experts reached consensus on 33 important items. Both rounds taken together delivered a consensus of 49 out of 123 items (39%).
Strategies Targeting Parents
Concerning strategies for interventions that target parents, experts agreed on eight important items during the second round and another 10 items during the third round ( Table 2 ). The strategies considered relevant can be categorized into the following: 1) parenting practices like setting rules, communication about alcohol, and monitoring of the child, and 2) parenting styles, such as being responsive and interested in the child.
Strategies Targeting Adolescents
A further goal of this study was to identify strategies to reduce binge drinking in adolescents in an intervention aimed at adolescents; these results are depicted in Table 3 . Experts agreed on three important strategies during the second round and on another four during the third round. Most prominent were strategies to increase refusal skills. Other strategies were related to coping with negative emotions, dealing with drinking in social situations, and developing decision-making skills.
Strategies to Reduce Drop-out of Adolescents
Concerning drop-out of adolescents, experts agreed on one important strategy during the second round and another 12 strategies in the third round. During the second round, experts only agreed on the importance of incentives. During the third round, strategies related to design and content of the intervention and the importance of reminders were emphasized ( Table 4 ).
Strategies to Reduce Drop-out of Parents
Concerning drop-out of parents, experts agreed on four important strategies in the second round and seven in the third round. Here the important strategies were related to the content and design of the intervention (e.g., usability, feasible recommendations, tailoring the intervention) and the use of reminders ( Table 5 ).