Background: Given that high levels of stress during adolescence are associated with negative consequences, it is important that adolescents with psychological needs are supported at an early stage, for instance with interventions at school. However, knowledge about the potential of school-based programs targeting adolescents with psychological needs, aimed at reducing school or social stress, is lacking. Objective: The current study aimed to investigate the effectiveness of two targeted school-based skills-training programs, addressing either skills to deal with performance anxiety or social skills. Methods: Two randomized controlled trials were performed with participants who self-selected to one of the programs. The sample comprised of N = 361 adolescents (M[subscript age] = 13.99 years, SD = 0.83) from various educational levels and ethnic identity backgrounds. The performance anxiety program included N = 196 participants (N = 95 in the experimental group), while the social skills program included N = 165 participants (N = 86 in the experimental group). MANCOVA's were performed. Results: The performance anxiety program had a small effect on reducing adolescents' test anxiety. Furthermore, for adolescents who attended more than half of the sessions, the program had small effects on reducing test anxiety and fear of failure. The program did not improve adolescents' coping skills or mental health. The social skills program was not effective in improving social skills, social anxiety, and mental health. Conclusions: A relatively short, targeted program addressing skills to deal with performance anxiety can have the potential to reduce adolescents' performance anxiety.