Using a new multidimensional model of relationship commitment, this study examined the association among attachment insecurities (avoidance and anxiety) and commitment (optimal, over, and under) in 159 relationally distressed, monogamous and mainly heterosexual couples. Dyadic analyses revealed that avoidant individuals reported less optimal and less over-commitment, as well as more under-commitment. Their partners also reported less over-commitment. Moreover, whereas anxious individuals reported more over-commitment, their partners reported less optimal commitment and more under-commitment. Moderation analyses showed that anxious individuals reported more optimal commitment when their partners reported very high levels of avoidance. The findings suggest nuanced implications for couple therapy.