Non-Hodgkin lymphoma (NHL) is amongst the most frequent cancer subtypes in children and in adults. However, there are major differences in the distribution of NHL subtypes between the pediatric and adult patient populations. At least for diffuse large B-cell lymphoma (DLBCL) recent data indicate that patient age at diagnosis correlates with molecular features of the lymphoma. Concerning treatment, in common pediatric protocols the same therapy is used for DLBCL and Burkitt lymphoma/leukemia (BL/B-AL). In adult patients, there is an established gold standard treatment for DLBCL, while the optimal treatment of BL/B-AL is under evaluation. Importantly, the correct diagnosis of the NHL subtype plays a crucial role in the treatment decision in adults with aggressive B-cell lymphoma. Adolescent and young adult patients are caught between the two age groups of children on the one hand and adults on the other. Whether the lymphoma biology and subtypes found in this age group resemble rather their pediatric or their adult counterparts is not yet answered. Also, systematic data on the optimal treatment for adolescents with lymphoma are lacking. Therefore, this article reviews current data on patient characteristics, biology, treatment and outcome, mainly in pediatric patients. These data are compared to those published for adult patients with B-cell NHL aiming to look for hints on optimal classification and treatment in adolescents and young adults with B-NHL.