The study aimed to describe the cost-effectiveness of a selected list of interventions for common neuropsychiatric disorders in a developing country. Using depression, schizophrenia, epilepsy, and hazardous alcohol use, a sectoral approach to cost-effectiveness analysis developed by the World Health Organization was contextualized to Nigeria. The outcome variable was the disability adjusted life years (DALYs). We found that the most cost-effective intervention for schizophrenia is a community-based treatment with older antipsychotic drugs plus psychosocial support or case management. The most cost-effective interventions for depression, epilepsy, and alcohol use disorders are older antidepressants, with or without proactive case management in primary care, older anticonvulsants in primary care, and random breath testing for motor vehicle drivers, respectively. Combined into a package, these selected interventions produce one extra year of healthy life at a cost of less than US $320, which is the average per capita income in Nigeria.