The practice of parent and child sharing a sleeping surface, or 'bed-sharing', is one of the most controversial topics in parenting research. The lay literature has popularized and polarized this debate, offering on one hand claims of dangers, and on the other, of benefits - both physical and psychological - associated with bed-sharing. To address the scientific evidence behind such claims, we systematically reviewed 659 published papers (peer-reviewed, editorial pieces, and commentaries) on the topic of parent-child bed-sharing. Our review offers a narrative wallcthrough of the many subdomains of bed sharing research, including its many correlates (e.g., socioeconomic and cultural factors) and purported risks or outcomes (e.g., sudden infant death syndrome, sleep problems). We found general design limitations and a lack of convincing evidence in the literature, which preclude making strong generalizations. A heat-map based on 98 eligible studies aids the reader to visualize world-wide prevalence in bedasharing and highlights the need for further research in societies where bed-sharing is the norm. We urge for multiple subfields anthropology, psychology/psychiatry, and pediatrics to come together with the aim of understanding infant sleep and how nightly proximity to the parents influences children's social, emotional, and physical development. (C) 2016 Elsevier Ltd. All rights reserved.