This study investigated associations between adult romantic attachment and couples’ conflict behaviors and the potential mediating role of intimacy. A community sample of 74 couples reported on their attachment security style on the Attachment Style Measure (ASM) (Simpson, 1990) and on multiple dimensions of intimacy on the Personal Assessment of Intimacy in Relationships (PAIR) (Schaefer & Olson, 1981). Couples’ conflict behaviors were assessed via behavioral observations and coded for positive and negative dimensions of conflict. Path analyses indicated numerous actor and partner effects in the links between attachment, intimacy, and conflict. For men, both avoidant and anxious attachment styles were predictive of their own and their partner’s intimacy. For women though, both secure and avoidant attachment styles were predictive of their own and their partner’s intimacy. For men, all domains of intimacy were predictive of their own or their partner’s conflict behaviors. For women, only emotional intimacy was predictive of conflict behaviors. All domains of men’s intimacy emerged as significant mediators of associations between attachment and couples’ conflict behaviors. For women, only emotional intimacy mediated these associations. Implications for the treatment of relationally-discordant couples are discussed.