Foster and adoptive parents often face challenges while taking care of children who, due to their adverse early life experiences, are at risk of developing insecure attachment relationships, behavior problems, and stress dysregulation. Several intervention programs have been developed to help foster and adoptive parents to overcome these challenges. In the current study, a series of eight meta-analyses were performed to examine the effectiveness of these intervention programs on four parent outcomes (sensitive parenting, k = 11, N = 684; dysfunctional discipline, k = 4, N = 239; parenting knowledge and attitudes, k = 7, N = 535; parenting stress, k = 18, N = 1,306), three child outcomes (attachment security, k = 6, N = 395; behavior problems, k = 33, N = 2,661; diurnal cortisol levels, k = 3, N = 261), and placement disruption (k = 7, N = 1,100). Results show positive effects for the four parent outcomes and child behavior problems, but not for attachment security, child diurnal cortisol levels, or placement disruption. Indirect effects on child outcomes may be delayed, and therefore long-term follow-up studies are needed to examine the effects of parenting interventions on children.