This study examined initial levels of attachment anxiety and avoidance, as well as their patterns of change, across eight sessions of couple therapy. Participants were 461 couples in a treatment‐as‐usual setting. Dyadic latent growth modeling was used to determine whether couples started therapy at similar levels of attachment anxiety and avoidance and whether attachment anxiety and avoidance changed. An actor partner interdependence model was used to see whether partner attachment anxiety was related to avoidance. Results showed relative stability of attachment anxiety and avoidance over the course of therapy, with the only change being a slight decline in attachment anxiety among women. Results showed that a person's attachment anxiety was not related to their partner's avoidance and vice versa.