Objective: This study examined attachment within the framework of cognitive behavioral therapy (CBT) for panic disorder with agoraphobia (PDA) by measuring the changes in avoidant and anxious attachment in a session-by-session analysis. Method: Thirty-one patients with PDA were treated using CBT. Pre-session data on attachment style (ECR), avoidance behaviors (MI-alone: MI-al; MI-accompanied: MI-ac), anxiety sensitivity (ASI), emotion regulation (ERQ), and working alliance (WAI) were collected. Mixed model analyses were conducted to estimate relationship between changes in attachment, PDA symptoms, and related measures. Results: Variables improved during therapy. Changes in ASI were positively related to changes in avoidant and anxious attachment. Changes in MI-al, but not MI-ac, were related to changes in ECR. Changes in ASI and MI-al predicted changes in ECR-anxiety in the following session, but not vice versa. Similarly, changes in avoidance behaviors and ERQ-suppression, preceded changes in ECR-avoidance unidirectionally. Whereas WAI significantly improved, its variability was related only to simultaneous changes in ECR-anxiety. Conclusions: Overall, avoidant and anxious attachment improved during CBT for PDA. This change was related to and preceded by improved anxiety sensitivity, avoidance behaviors, and emotion regulation. These findings suggest that CBT for panic probably has downstream effects on attachment representations.