The influence of family relations, maternal occupational characteristics, and childcare1The UK terms "childcare," childcare centres' and "nurseries" are used throughout this paper to define group care for children prior to starting their first year of formal schooling at age 4 years and are used synonymously with the American terms "day-care" and "preschool." This form of group care is provided in a formal setting, outside the family home and excludes "childminding" (i.e., childcare that may be group based and offered at the home of the care provider/childminder). In the UK, this form of childcare is offered from zero to 4 years old. Children are separated according to their age into small groups usually consisting of 10-15 children. In the present study, all children were in the preschool-aged group (3-4 years old). Where childcare of a different or more generic form is referred to, then this has been made clear in the context or stated in the text. utilization on preschool children's cortisol production were investigated in 56 mother-child dyads. Family characteristics and maternal employment, childcare and child temperament were reported by mothers. Morning and evening levels of children's salivary cortisol were obtained. Children in highly expressive or reserved families exhibited higher cortisol levels compared to children in moderately expressive families. Elevated levels of cortisol were detected in children of mothers reporting low levels of job role quality or high levels of emotional exhaustion. Frequent childcare use was found to protect children against the physiological effects of low maternal job role quality and emotional exhaustion. Findings underscore the pervasive role of the family as set within an external support system and highlight the potential physiological impact of these interacting contexts for children. Further research is needed to fully understand current findings and to develop appropriate psycho-physiological interventions.