Attachment theory has been a staple in our understanding of both child development and parent-child relationships. Despite this foundational value early attachment research from both Bowlby (1969) and Ainsworth (1979) focused on mother-child attachment. Research has expanded to include father-child attachment relationships as well, but studies consistently examine these wo relationships separately. This dissertation seeks to integrate family systems theory and attachment theory to explore how the similarity and differences between multiple attachment relationships, termed attachment concordance, impact other domains of family functioning such as dyadic adjustment and coparenting. Prior research suggests that the more secure relationships present the greater the benefit conferred. However, there is also some evidence that a mismatch in attachment relationships may create unique stress and competition between partners. The first study explores how changes in dyadic satisfaction over the transition to parenthood are related to the concordance of mother-child and father-child attachment. Results indicate significant differences in marital satisfaction between couples in which mother and father develop a secure relationship and couples in which only one parent develops a secure attachment relationship with the new baby. The second study explored how the pre-birth concordance of attachment adult predicted changes in marital satisfaction pre and postnatally. This study also analyzed how pre-birth adult attachment concordance predicted self-reported coparenting scores at one year. This study did not produce any significant results. Taken together these studies underscore the value in examining multiple attachment relationships at once instead of treating these relationships as isolated variables. Further these results demonstrate the unique patterns of family functioning that can emerge when partners have discordant attachment relationships.