Efficacy beliefs and communication are key constructs that have been targeted to develop task cohesion. This study’s purpose was to (a) examine whether collective efficacy, team-focused other-efficacy, and team-focused relation-inferred self-efficacy are predictive of task cohesion and (b) evaluate the possibility that communication mediates efficacy–task cohesion relationships. British university team-sport athletes (N = 250) completed questionnaires assessing efficacy beliefs, communication (i.e., positive conflict, negative conflict, and acceptance communication), and task cohesion (i.e., attractions to group, group integration). Data were subjected to a multigroup path analysis to test mediation hypotheses while also addressing potential differences across males and females. Across all athletes, collective efficacy and team-focused other-efficacy significantly predicted attractions to group and group integration directly. Positive conflict and acceptance communication significantly mediated relationships between efficacy (team-focused other-efficacy, collective efficacy) and cohesion (attractions to group, group integration). Findings suggest that enhancing athletes’ collective efficacy and team-focused efficacy beliefs will encourage communication factors affecting task cohesion.