The role of relationship authenticity in shaping women's daily condom use was investigated. Forty‐seven sexually active women in dating relationships completed a measure of relationship authenticity and then reported on their daily condom use and relationship events for 14 consecutive days. Inauthentic women were less likely than more authentic women to use condoms, particularly on days with frequent negative events such as major disagreements with a romantic partner. These critical Person × Situation interactions remained significant after controlling for the use of another form of birth control, sexual frequency, knowledge of a partner's sexual history, and relationship satisfaction. Implications for sexual risk‐taking behaviors and future research using daily experience methods to study sexuality in dating relationships are discussed.