Factors related to successful functioning of single parents have not been identified. In this study, relationships among sources of social support and criterion measures of functioning were examined. To isolate the role of social support, a population was selected that was relatively homogeneous on variables considered important in coping with single parenthood: economic status, educational or vocational opportunities, access to day-care, and length of time as a single parent. A check list and structured interview were administered to 30 unmarried women to determine their sources of social support. Ratings of parenting adequacy and of the preschool child's emotional development and behavior by three professional staff members at the day-care centers were used as criterion measures of functioning. Based on the staff ratings, the adequately functioning group was distinguished from the inadequate one. Significant correlations were found between these staff ratings and one social support variable: support from talking with network members. Key sources of social support were identified through discriminant analyses.