In this review, we describe the development of prosocial behavior in adolescence as a critical inflection period for social adjustment. Experimental research using prosocial giving tasks demonstrates that adolescents differentiate more between recipients and contexts, suggesting increasing ingroup-outgroup differentiation during adolescence. We also demonstrate that social brain development during adolescence is partly driven by environmental influences, further underlining adolescence as a critical period for social development. The COVID-19 pandemic has had and will have long-term effects on the current generation of adolescents, for which we describe both the risks, resilience factors, and opportunities for engaging in prosocial acts of kindness.