The objective of the present research was to examine the contribution of two intervention components, social skills training and problem solving training, to alcohol- and drug-related outcomes in a school-based substance use prevention program. Participants included 341 Spanish students from age 12 to 15 who received the prevention program Saluda in one of four experimental conditions: full program, social skills condition, problem solving condition, and a wait-list control group. Students completed self-report surveys at the pretest, posttest and 12-month follow-up assessments. Compared to the wait-list control group, the three intervention conditions produced reductions in alcohol use and intentions to use other substances. The intervention effect size for alcohol use was greatest in magnitude for the full program with all components. Problem-solving skills measured at the follow-up were strongest in the condition that received the full program with all components. We discuss the implications of these findings, including the advantages and disadvantages of implementing tailored interventions to students by selecting intervention components after a skills-based needs assessment.