University programmes increasingly implement small-group teaching, with the assumption that students' social capital fosters academic achievement. However, few studies address the impact of social capital on the study success of first-year students. The current study addresses this research gap, examining the extent to which social capital relates to study success for first-year university students and whether this effect differs for high-, average-, and low-achieving high school students. Survey data collected from 407 first-year university students' measure social capital in terms of family, faculty, and peers. Path analysis reveals that in contrast to family capital, peer capital (help seeking, collaboration, and fellow students' support) and faculty capital (mentor support) contribute positively to study success, indirectly through friendship or self-efficacy. For high achievers, compared with low achievers, friendship has a positive effect on study success during the first year. Small-group teaching seems beneficial for study success if it enhances students' social capital. (C) 2016 Elsevier Inc. All rights reserved.