Although beliefs, self-efficacy, and intention to quit have been identified as proximal predictors of initiation or quitting in young adults, few studies have studied how these variables change after a smoking cessation intervention. To evaluate the changes in the beliefs, self-efficacy, and intention to avoid smoking and determine if these are potential mediators in quitting, following a smoking cessation intervention, aimed at tobacco-dependent college students. Single-blind, pragmatic randomized controlled trial with a 6-month follow-up. A total of 255 smoker students were recruited from September 2013 to February 2014. Participants were randomly assigned to intervention group (n = 133) or to control group (n = 122). The students in the intervention group received a multicomponent intervention based on the Theory of Triadic Influence (TTI). The strategies of this program consisted of a 50 min motivational interview conducted by a nurse and online self-help material. The follow-up included a reinforcing e-mail and group therapy. The smoking-related self-efficacy, belief, and intention scale was used to assess outcomes. Intention to quit smoking is partial moderator explaining 36.2% of the total effects in smoking cessation incidence. At 6 month follow-up, the differences in the mean scores of self-efficacy and intention related to stopping smoking were significantly higher in the intervention than in the control group. A multicomponent intervention based on the TTI, tailored to college students, positively increased the self-efficacy to avoid smoking and the intention to quit, suggesting intention as potential mediator of quitting.