Self-esteem is an individual's ability to describe his situation, both positive and negative. Adolescence is an important period for the formation of self-esteem. The more individuals are able to describe positive abilities about themselves, the higher the level of self-esteem of the individual. Conversely, the higher the individual's ability to describe negative abilities in himself, the lower his self-esteem. Low individual self-esteem can be caused by the inability to be assertive towards others. Therefore, assertive training (assertive training) is important to be carried out on an ongoing basis. By doing assertive training, adolescent expected to be able to increase their self-esteem and avoid bullying by their peers. The research method used is literature review and documentation techniques as data collection. The data collected is related to the research problem being studied, namely assertiveness training to increase adolescent self-esteem. The results of the study found that assertive training was effective in increasing adolescent self-esteem.