Postseparation coparenting is decisive in the adjustment of families going through parental separation, which supports the necessity to gain a better understanding of the factors influencing this coparental relationship. This meta-analysis of 13 studies first examines the magnitude of the association between child custody and postseparation coparenting (conflict and cooperation). A second objective of this meta-analysis is to explore the influence of potential moderating variables, such as the time elapsed since the separation, the parent who has sole custody, the informant of the outcome variable, and the study’s publication year. Findings show that parents with joint custody exhibit more cooperation than those with sole custody. However, it appears that having joint or sole custody has no influence on the level of conflict between two coparents. Interpretation of these results is quantified by the fact that the majority of the variables considered in terms of moderators act to modify the relationship between child custody arrangements and postseparation coparenting. This suggests that the development of less conflictual and more cooperative postseparation coparenting does not depend on a single factor, such as the type of custody arrangement, but on numerous interrelated factors. Future research and interventions should focus on the dynamics of the interaction of factors influencing postseparation coparenting. It is also important to take into account the limitations of such studies in the understanding of the subject, including limitations related to operational definitions of child custody arrangements. (PsycINFO Database Record (c) 2019 APA, all rights reserved)