This study examines the extent to which knowledge sharing self-efficacy, motivation and sense of community variables predict undergraduate students' knowledge sharing behaviors (knowledge receiving and knowledge giving) in online learning environments. The participants included undergraduate students (N = 284) from two different universities in Turkey. Stepwise multiple regression analyses were carried out to identify the variables predicting knowledge sharing behaviors as knowledge giving and receiving behaviors. The results revealed that both knowledge giving and receiving behaviors were best predicted by knowledge sharing self-efficacy, followed by motivations and sense of community. External effects and growth of aim affected knowledge receiving, whereas only internal effects affected knowledge giving. The independence factor has a negative effect on knowledge receiving, yet has a positive effect on knowledge giving.