Objectives: Several attempts to reduce the incidence of sport injuries using psychosocial interventions produced fruitful, although inconclusive results. This paper presents the effectiveness and implementation issues of a pilot 3-month stress-management and muscle relaxation program aimed at reducing sport injury incidence. Design: Pre-post treatment-non treatment group comparison. Program administration: The program was administered by a trained psychologist on a once-a-week, 1-h session basis. Participants: Seventy-four male soccer players from four National Youth league teams voluntarily participated. Teams were randomly assigned to either treatment/non-treatment group. Measures: Injury protocol, Self-monitoring cards, Athletes' satisfaction and commitment survey, Coaches' interview. Results: Group main effect and Time-Group interaction effect were both statistically significant, F(1,60) = 830, p = 0.005, eta(2)(p) = 0.121, with the average number of injuries larger in the post-treatment phase of non-treatment group (p = 0.005, eta(2)(p) = 0.077). There was a significant decrease in the average number of injuries for the intervention group before and after implementing the program (p < 0.001, eta(2)(p) = 0309). Conclusions: A controlled implementation of a psychosocial program was effective in reducing youth soccer sport injuries, with a high level of satisfaction and commitment from the athletes, as well as high acceptance from the coaches. (C) 2016 Elsevier Ltd. All rights reserved.