Adolescence is a sensitive developmental period characterized by cognitive, emotional, and social changes, along with challenges such as identity formation, the need for belonging, and sensitivity to rejection. Adolescent girls, due to biological and social factors, are more vulnerable to anxiety, self-criticism, body image concerns, and relational difficulties. Self-acceptance refers to a realistic recognition and acceptance of one’s strengths and weaknesses without dependence on external validation, and it is associated with better mental health and relationships; low levels are linked to anxiety, depression, and vulnerability.



Loneliness is a subjective experience resulting from a gap between desired and actual relationships. It is prevalent during adolescence and more common among girls. This feeling is associated with negative psychological and physical outcomes and may become chronic. Research indicates that low self-acceptance and loneliness reinforce each other in a negative cycle.



Various interventions such as social skills training, cognitive-behavioral therapy, and mindfulness have been used to address these issues. Mindfulness-based schema therapy is an integrative approach that combines modification of deep cognitive patterns with nonjudgmental awareness, helping improve emotion regulation, reduce self-criticism, and enhance self-acceptance.



Despite evidence supporting its effectiveness, few studies have examined its simultaneous impact on self-acceptance and loneliness in adolescent girls. The present study aims to investigate the effectiveness of this intervention in reducing loneliness and increasing self-acceptance among girls aged 12 to 15 using a quasi-experimental design with a control group.