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.Pre-post treatment-non treatment group comparison.The program was administered by a trained psychologist on a once-a-week, 1-h session basis.Seventy-four male soccer players from four National Youth league teams voluntarily participated. Teams were randomly assigned to either treatment/non-treatment group.Injury protocol, Self-monitoring cards, Athletes' satisfaction and commitment survey, Coaches' interview.Group main effect and Time-Group interaction effect were both statistically significant, F(1,60) = 8.30, p = 0.005, η2p = 0.121, with the average number of injuries larger in the post-treatment phase of non-treatment group (p = 0.005, η2p = 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, η2p = 0.309).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.