The aim of the study was to examine relationships between psychosocial family- and school environment and personality as assessed by the Junior Eysenck Personality Questionnaire (EPQ-J) and possible personality interactional effects. The study was based on 244 Swedish girls and boys, 10 - 19 years old, who filled in the Family- and School Psychosocial Environment (FSPE) questionnaire and the EPQ-J. A multiple regression analysis showed that the FSPE-factor family conflicts and school discipline predicts psychoticism (antisocial personality), and that the FSPE-factor warmth, support and openness from parents, siblings and peers predict extraversion. Sex, psychoticism and the size of sibling group predicted neuroticism. Spanking was reported in various degrees by 8.1 percent of the children, and this factor was related to psychoticism. These results support socialization theories. The most unexpected finding was the impact of interactions between personality variables themselves, influencing the FSPE’s predictability of neuroticism. Discussion about the advantage of the use of statistic control in a multiple regression, possible causal links between psychosocial environment and personality, limitations and further research propositions concludes the article.