This study investigated the psychosocial adjustment and anxiety of adolescents during a 7-month exercise intervention programme. In addition, extensive research on the psychosocial adjustment of adolescents during intense physical activity was performed. The experimental group included adolescent girls (n = 110) and boys (n = 107) aged between 14 and 15 years while the control group included adolescent girls (n = 99) and boys (n = 112) of the same age group attending the same school. The girls and boys in the EG participated in modified physical education lessons two times a week. Once a month they received a theory class where they were taught about communication disorders of adolescents and ways of preventing them by means of physical activities. In practical classes, the girls and boys in the EG had sports and games (basketball, volleyball and football) as well as Pilates, enhancing physical abilities. The measurement of psychosocial adjustment included the modification method developed by Roger and Daimond. The measurement of anxiety, the methodology of Reynolds and Richmond. In summarising the results of the 7-month exercise intervention programme of enhancing psychosocial adjustment and its components (self-esteem, dominance, positive self-evaluation, emotional comfort, internality, and evaluation by others) and decrease in anxiety in physical education lessons, we can state that after the intervention there are certain tendencies towards improved psychosocial adjustment that assists in overcoming various critical situations.