This chapter explores the psychological mechanisms underlying group work in higher education, with emphasis on group cohesiveness, the attraction and motivation that bind members together. Cohesion, fostered by shared purpose, time, and communication, supports collaboration but may also encourage groupthink, where conformity suppresses critical evaluation. Groupthink arises from concurrence-seeking behaviour, heightened by strong identity and structural deficiencies. While identity fosters commitment, unchecked identification risks depersonalisation and weakened moral reasoning. The chapter also considers motivational forces such as social facilitation, where observation enhances performance, and the Köhler effect, where weaker members increase effort when indispensable. Cultural context and task type further shape group identity, social loafing, and overall outcomes.