Team building (TB) is recognized as one of the most prevalent and promising group-development interventions applied in sport. However, most coaches lack the necessary information to effectively and efficiently target and enhance specific group characteristics and processes. The aim of this study was to develop and apply the Team Environment AssessMent (TEAM) to better inform a TB intervention. Twenty-three male adolescent athletes (mean age 17.9 years) from an elite hockey team completed the TEAM and measures of cohesion before and after a TB intervention. Based on initial TEAM scores, role acceptance and leadership were identified and purposefully targeted in the TB intervention. Athletes’ perceptions of role acceptance, leadership, and task cohesion were stronger after the TB intervention. Furthermore, follow-up interviews with team members and coaches provided additional empirical support for the utility of the TEAM to assess and enhance the efficiency of a TB intervention in sport.