We investigate the relations between gender, parental education, ability, and educational achievement in Britain, focusing on the way in which gender and parental education interact with ability to contribute to a pupil's obtaining secondary school qualifications. This allows us to provide evidence relevant to claims concerning the effects of differences in the way in which working- and middle-class familial cultures interact with gender-specific behaviour in school. Given the configurational nature of the processes likely to be involved, we employ Ragin's Qualitative Comparative Analysis as our method. We find that, in both academically selective and non-selective schools, high ability is a quasi-sufficient condition for obtaining certain levels of qualification, but that at lower levels of ability, either being female or having highly educated parents (or both) have to be present, too. Boys without highly educated parents perform less well than girls from a similar background. (Contains 2 figures, 4 tables and 19 notes.)