In two studies in daycare centers, we investigated a newly developed index for flexible child care describing parents' use of evening care and flexible attendance scheduling for their child. We examined the relation between this index together with stability in care, mother's stress and the child's temperament on the one hand, and quality of caregivers' behavior and a child's socio-emotional functioning in day care on the other. In Study I, the mothers and caregivers of 186 children (aged 6-30 months) participated in a survey. In Study II, approximately 18 months later, 52 children from Study I were observed in their daycare setting. Children showed more well-being in day care when they had few parallel care arrangements, and when there was more daily stability in staffing and grouping patterns. Unexpectedly, caregivers in groups with more stability in staffing and grouping patterns, showed less positive caregiving behavior. When staff turnover rate was higher, positive caregiving behavior was lower. Finally, children in more flexible child care showed more non-compliance. © 2003 Elsevier Science Inc. All rights reserved.Keywords: Day care; Flexible child care; Non-standard hours child care; Stability in care; Socio-emotional functioning; Quality of careIn recent years, parents using the services of center day care have urged child care centers to extend their child care facilities, i.e., to make them more "flexible," in order to enable the parents to optimally combine work and family demands. Parents nowadays frequently work for organizations that operate early mornings, evenings, nights and weekends as well as