Children at times play key roles in legal cases as victims of or witnesses to crimes. This is most notable in criminal cases involving alleged sexual abuse. It also occurs with cases involving other types of crimes, both in criminal and juvenile dependency courts, the latter when children are suspected of having been exposed to intrafamilial maltreatment. Involving children is complicated, due to their prior experiences of trauma and their incomplete cognitive or socioemotional development and dependence on family members and legal authorities for assistance. How both the criminal and dependency systems involve children and the consequences of that involvement for children and the pursuit of justice have been heavily debated. This chapter reviews extant research concerning children’s participation in criminal and dependency proceedings as victims or witnesses. It includes a discussion of methodological issues that arise when pursuing this research, as well as findings concerning both the socioemotional and attitudinal consequences of children’s participation. The chapter closes with suggestions for future research and legal recommendations.