This review examined risk and protective factors associated with placement breakdown across k = 26 studies of 20,650 children in foster families. A series of meta-analyses were performed to assess the average effect sizes across multiple studies on the same factors. Older age at placement (k = 15), behavior problems (k = 13), a history of residential care (k = 7) and previous placements (k = 6) showed significant small to moderate associations with placement breakdown. A large combined effect size was found for behavior problems when analyzed in multivariate models. Unexpectedly, kinship care (k = 6) did not show a significant association with placement breakdown. Other potential protective factors of placement breakdown referred to the quality of foster caregiving and other foster care related aspects, which showed small to large effect sizes. However, findings were contradictory when univariate and multivariate results were compared. Results of multivariate studies suggested mediating and moderating effects of variables related to the children's background. This might suggest that more insight in the processes leading up to placement breakdown may be derived from causal models. © 2006 Elsevier Ltd. All rights reserved.