The involvement of nonparental adults (NPAs) in the upbringing of children is widely considered to be important for the well-being of both children and parents. However, there has been no systematic overview of parental and nonparental perspectives toward this involvement. This study presents an overview of the international literature on sharing responsibility between parents and NPAs. A structured search resulted in the inclusion of 49 relevant publications. Limitations of the extant research notwithstanding, some generalizations about shared childrearing can be made. However, many issues relating the taboo of sharing childrearing responsibilities remain poorly understood. To break the taboo, future research should further explore the underlying sensitivities.