Background: The proper forming and well-being of adolescents is crucial to the development of a country through its potential contribution to economic prosperity. Adolescents aged between 10 to 19 are in the crucial stage of formation of the right personality and character leading to social responsibility. Thus, these early years are important in shaping them for successful investment and intervention in their later years. This study presents baseline cross-section findings from the randomized controlled intervention that aimed at testing the effect of Problem-based Learning (PBL) on non-cognitive skills (abstinence skills, condom use negotiation, self-esteem, and assertiveness) for safe sexual behavior among adolescents in Tanzania mainland. Methods: The study employed an analytical cross-section design that adopted a clustered quantitative research approach of 647 randomly selected respondents and was conducted between September and December 2019.