Findings are presented of the second phase of a longitudinal study of families created by single mothers by choice. Forty-four single heterosexual mothers were compared with 37 partnered heterosexual mothers, all with a donor-conceived child aged around 8-10 years. Standardized interview, observational, and questionnaire measures of maternal wellbeing, mother-child relationships and child adjustment were administered to mothers, children, and teachers. There were no differences in maternal mental health, the quality of mother-child relationships or children's emotional and behavioral problems between family types. However, higher levels of parenting stress and higher levels of children's prior adjustment difficulties were each associated with children's adjustment difficulties in middle childhood irrespective of family type. The findings suggest that the presence of two parents-or of a male parent-is not essential for children to flourish, and add to the growing body of evidence that family structure is less influential in children's adjustment than the quality of family relationships. (PsycInfo Database Record (c) 2021 APA, all rights reserved).