This study describes a team building intervention and the effects on team cohesion in adolescent elite football players. The team building group (3 teams, n = 55) attended 12 weekly 60-minute team building sessions, while the control group (3 teams, n = 57) did not. The intervention used the work of Carron and Spink (1993) and Carron, Widmeyer and Brawley (1985) to plan and conduct a practically sound and effective intervention. A Danish version of the Group Environment Questionnaire was used to measure social and task cohesion at baseline and at the end of the intervention, and qualitative interviews with the participants were conducted. Results show that the sub-variable group integration–social increased significantly from baseline to end of intervention in the intervention group compared to the control group. The qualitative analysis indicated that the intervention had an effect on the intervention group. Results are discussed regarding practical implications and research.