The focus of this thesis is economic evaluations of programs and interventions regarding children and adolescents with mental health issues, victimization, and intellectual disabilities (ID). The first paper examines a potential link between mental health issues among adolescent and the class-size of the school class they are enrolled in. The class-size and schools’ financial resources is often at the center of policy debates. Our results suggest that there is no evidence that larger classes have negative impact on the mental health for adolescents in a Swedish context. The second paper investigate the societal willingness to pay (WTP) to reduce bullying in Swedish schools. The results suggest that the tax payers WTP is about 5 SEK and the societal is about 600 000 SEK per reduced bullying victim. This value of WTP could be used as a measure to evaluate different investments in anti-bullying programs and efforts to reduce the bullying in schools. The third paper estimates the cost-effectiveness of one recently introduced antibullying program, the Finnish KiVa program, one of the few evidence based programs in the world. Based on a decision-analytic model, the results indicate that the KiVa program is a cost-effective program that has a cost per reduced victim well below the WTP as estimated in the second paper as documented above. The fourth paper evaluates, from the municipality perspective, the effects of investing in a SE program compared to “business as usual” in order to increase the likelihood for gaining regular employment for the pupils with ID. The results indicate that it takes 9 years before breakeven is reached if investing in the SE program. The fifth paper conducts a decision-analytic economic evaluation of the SE program using simulations to assess the effects over the full life-course. The results suggest that from a societal perspective the program is cost-effective ten years after the investment and by then has generated a benefit of 17 000 SEK per individual.