The aim is to present the measurement validity and reliability of a scale measuring children's and adolescents’ self-, peer-, teacher-, and parent evaluated social competence, and further on to study, whether these evaluations predict later psychosocial ill-being consisted of loneliness, social anxiety, social phobia, school burn-out and depression. First, we present the validity indices of the social competence scale and consistency between the evaluators and between the social competence factors (co-operating skills, empathy, impulsivity, disruptiveness). Further on, we present structural equation models of 10- and 13-years old students’ multisource evaluated social competence in relation to their psychosocial well-being one year later. According to the preliminary results children’s negative self-image of their antisocial behavior during 4th grade predicted higher levels of loneliness and social anxiety during 5th grade. Moreover, the parental perceptions of child’s lack of prosocial behavior predicted higher levels of loneliness and social anxiety. On the contrary, for lower secondary education adolescents, the teacher- and especially the peer ratings during the 7th grade predicted loneliness, social anxiety, social phobia and school burn-out during 8th grade. The results will be discussed in the light of school curriculum, pupils´ motivational orientation and learning outcomes.