Objective: Web-based brief alcohol interventions have the potential to reach a large number of individuals at low cost; however, few controlled evaluations have been conducted to date. The present study was designed to evaluate the efficacy of gender-specific versus gender-nonspecific personalized normative feedback (PNF) with single versus biannual administration in a 2-year randomized controlled trial targeting a large sample of heavy-drinking college students. Method: Participants included 818 freshmen (57.6% women; 42% non-Caucasian) who reported 1 or more heavy-drinking episodes in the previous month at baseline. Participants were randomly assigned in a 2 (gender-specific vs. gender-nonspecific PNF) x 2 (single vs. biannual administration of PNF) + 1 (attention control) design. Assessments occurred every 6 months for a 2-year period. Results: Results from hierarchical generalized linear models provided modest effects on weekly drinking and alcohol-related problems but not on heavy episodic drinking. Relative to control, gender-specific biannual PNF was associated with reductions over time in weekly drinking (d = -0.16, 95% CI [-0.02, -0.31]), and this effect was partially mediated by changes in perceived norms. For women, but not men, gender-specific biannual PNF was associated with reductions over time in alcohol-related problems relative to control (d = -0.29, 95% CI [-0.15, -0.58]). Few other effects were evident. Conclusions: The present research provides modest support for the use of biannually administered web-based gender-specific PNF as an alternative to more costly indicated prevention strategies. (Contains 5 tables, 1 footnote and 4 figures.)