The objective of the present study was to examine the contribution of three intervention components (public commitment, resistance to advertising, and leisure promotion) on alcohol and protective variables in a school-based substance use prevention program. Participants included 480 Spanish students aged from 14 to 16 who received the "Saluda" prevention program in one of the following five experimental conditions: complete program, program minus public commitment, program minus resistance to advertising, program minus leisure promotion, and a waiting-list control. The students completed self-report surveys at pretest, posttest, and 6-month follow-up assessments. When excluding the healthy leisure promotion component, the "Saluda" program showed no loss of efficacy neither on alcohol use nor on other substance-related variables, while public commitment and resistance to advertising improved the aforementioned program's efficacy.