Sleep is not a solitary activity for the majority of adults, this impacts sleep quality, health, and well-being. Couples experience sleep concordance, or a synchronization of sleep-wake times, which can improve and diminish sleep quality (Gunn et al., 2015). This study explores the association between sleep concordance and sleep quality by examining attachment style as a moderator. Daily sleep diaries were completed by 179 heterosexual couples. Sleep concordance was calculated by dividing total time partners were in bed together by total time at least one partner was in bed each day. Data were analyzed using a multilevel model described by Bolger and Laurenceau (2013). There was a positive association between daily sleep concordance and sleep quality for men. Women with higher secure attachment style scores reported greater sleep quality, and women with higher insecure attachment style scores reported lower sleep quality. Among women with higher secure attachment style scores and lower avoidant attachment style scores there was a negative association between mean sleep concordance and sleep quality. There was no association between sleep concordance and sleep quality for higher anxious attachment scores. Future research is needed to address causal relationships. Findings indicate men and women may experience sleep concordance differently.