Youth sport has long been considered an appropriate context to foster competence, confidence, connection, and character of its participants (4C's: Côté, Bruner, Erickson, Strachan, & Fraser-Thomas, 2010). To promote youth sport development, coaches have used strategies that are inspired by a humanistic or athlete-centered coaching philosophy (Lyle, 2002). However, the principles of humanistic coaching are not taught in coach training programs, which has led to inconsistent coaching practices and limited the evidence to support its effectiveness (Nelson, Cushion, Potrac, & Groom, 2014). As such, the purpose of this study was to assess the development of youth sport athletes who were coached by individuals trained in the use of humanistic coaching principles. A sample of 148 athletes (mean age=13.63, R=12-17) was divided into an experimental and control group. The athletes completed a set of five questionnaires (cf. Vierimaa, Erickson, Côté, & Gilbert, 2012) to measure competence, confidence, connection to coach, connection to peers, and character. The questionnaires were administered at both the beginning and end of the season. Two-way mixed ANCOVAs were performed using participants' scores from the beginning of the season as covariates. The results indicated the experimental group showed significantly higher levels of connection to their coaches [F(1,109)=4.328, p=0.04, h2=0.038] and character [F(1,109)=2.355, p=0.027, h2=0.044]. These findings suggest that coach training programs that address humanistic principle are effective in teaching coaches to promote youth development in sport. More specifically, they can impact coaches' practices and promote particularly connection and character.