Qualitative interviews with young women attending community colleges were used to address why women who do not desire pregnancy vary in how consistently they use contraception. Based on our analysis of the women's sexual histories, we argue that five factors are key to promoting or discouraging consistent use of contraception: efficacy (women's ability to put an intention to contracept into practice), the actions and attitudes of male partners, being in a long-term relationship, whether women experience side effects, and misinformation or erroneous reasoning about pregnancy risk. Variations in how these factors combine at different times in women's lives explain much about their patterns of contraceptive consistency.