The main question in this article is: Do differences in socialization conditions offer an explanation for the negative effect of one-parent families on children's educational attainment? The research design was an ex post facto experiment based on matched pairs, in which the experimental group (children from mother-headed families) and the control group (children from two-parent homes) were individually matched on variables known to influence educational attainment (sex, age, IQ and achievement, number of siblings and SES). Hypotheses regarding children's behavior and mothers' parenting behaviour were tested in 84 pairs of children and their mothers, and in 44 pairs of children and their mothers, respectively. The results showed less perceived strictness in mother-headed families, 'contrary' behaviour with respect to school on the part of their children, mothers less persistent in realizing educational ambitions, and a less positive perception of the mothers' parenting competence, all factors which appeared to negatively influence the children's school career. In addition, children from mother-headed families had lower scores on 'rule-competent' behaviour at home and at school, compared to children from two-parent homes. The parenting behaviour of the mothers in the one-parent and two-parent families differed on indicators of 'control', but not of 'support'. Socio-economic status (mother's educational and occupational level, employment, income) and social network ('closure' of the parental community) appeared to affect the rule-competent behaviour of mother-only children.