This study examined the effectiveness of a longitudinal 5C coaching intervention (Harwood, 2008), focused on promoting behavioral responses associated with commitment, communication, concentration, control, and confidence in youth soccer players. Five players, their parents and a youth academy soccer coach participated in a single-case multiple-baseline across individuals design with multiple treatments. Following baseline, the coach received sequential education in the principles of each C subsequent to integrating relevant strategies in their coaching sessions. During the five intervention phases, players completed assessments of their behavior in training associated with each C, triangulated with observationbased assessments by the coach and the players’ parents. Results indicated psychosocial improvements with cumulative increases in positive psychosocial responses across the intervention for selected players. Changes in player behavior were also corroborated by parent and coach data in conjunction with postintervention social validation. Findings are discussed with respect to the processes engaged in the intervention, and the implications for practitioners and applied researchers.