Historically, breadwinning is linked to cultural ideologies about masculinity and fatherhood, suggesting contemporary breadwinner mothers confront a gendered cultural ideal. I draw on 42 in-depth interviews with mothers and fathers in 21 couples in which women provide 80% to 100% of the family income to better understand mothers’ breadwinning. Few mothers self-identify as providers; just 38% of women (and their husbands) reported that wives were the family’s primary financial provider. Interviews indicate that while these mothers feel financial pressures similar to those reported by male breadwinners, their experience can also be characterized by the role it plays in undermining husbands’ masculinity and in deepening conflicts between employment and mothering. Overall, while adopting gender-atypical roles may promote change in the direction of greater equality, as when mothers get more serious about paid work or feel accomplishment as a breadwinner, this process is constricted by embedded cultural ideals of mothering and masculinity.