Combined Intervention of Long-term Letter Mentoring and Centralized Summer Camp by University Student Volunteers for Disadvantaged Children: A Randomized Controlled Trial

"A two-phase behavioral intervention aimed at improving psychological resilience among socioeconomically disadvantaged adolescents. The intervention includes:~1. a 5-day structured summer camp led by trained university student volunteers, featuring psychoeducational group sessions, emotional expression activities, and life skills training, based on SEL, CBT, and positive psychology frameworks; and~2. a 10-month pen-pal letter-writing component, where each child is matched with a trained university volunteer to receive monthly supportive letters. This stage reinforces the gains from the summer camp through sustained emotional support, skill reminders, and positive guidance.~The intervention is designed to be low-cost, scalable, and ethically safe, and has been standardized through manuals and training protocols."