Educators try to use social network services (SNSs) in their teaching because they are regarded as beneficial to student learning. However, little research to date has empirically investigated whether the use of an SNS increases university student learning outcomes. A total of 730 university students in the capital area of South Korea participated in the present study. Based on social learning theory, we developed a general structural model that included SNS participation (SP) as an exogenous variable and a range of endogenous variables: cognitive domain learning outcomes, affective domain learning outcomes, social domain learning outcomes, social acceptance (SA) and attitude towards university life (AT). The study results confirmed that the model adequately explained causal relationships between student learning outcomes and SA, AT and SP. SA was identified as a key variable because of its direct effect on learning outcomes. However, SP was considered more important because of its large indirect effects on all learning outcomes through both SA and AT.