Mothers and infants sleeping within proximity to each other (co-sleeping) represents normal, healthy, and expectable human behaviour, especially if mothers breastfeed. Yet, western health officials generally recommend against particularly one form of co-sleeping known as bedsharing. This study explores these issues and especially highlights parental accounts of their sleep practices, interpretations, and reflections based on detailed narratives or ‘ethnohistories.’ The sample involves a self-selected sub-group of over 200 mostly middle-class mothers from Canada, the United States, Australia, and Great Britain. Mothers report how and why they adopted co-sleeping practices, how satisfied they are (or were) with their decisions, and what benefits they think they or their infants derived from their co-sleeping practices. Also included in the reports are a surprisingly high number of parents who think they may have saved their infant's life by bedsharing, data heretofore never reported in the literature. The formulation of medical policies, we suggest, ultimately must be informed by a full understanding of how parents actually think about and subsequently structure their infant's sleep, what their goals and expectations are, and by an awareness of the emotional factors motivating parents to choose certain sleeping arrangements over others. The results reveal that many factors coalesce, often in unique ways, under unique circumstances, family by family, to determine where babies sleep and why. We conclude that sleeping arrangements are not solely determined by medically based recommendations, but also by the method of feeding, the particular needs of a particular infant, and the needs of mothers and fathers to get more sleep. While baby sleep locations and sleep patterns change in the first year of life, nighttime sleeping arrangements almost always reflect the nature of family values and the quality of social relationships at any given time. We conclude that these factors, alongside widely known independent SIDS risk factors, must also be acknowledged and respected if we are ever to achieve an effective and inclusive public health approach to the question of creating safe sleep environments for infants and children. Copyright © 2007 John Wiley & Sons, Ltd.