Background: The relevance of attachment theory to clinical practice was posited by Bowlby in his seminal work on Attachment and Loss. He likened the role of the therapist to that of an attachment figure and proposed that the course and outcome of therapy would be affected by the internal working models (IWM's) of both the patient and the therapist. A small number of studies have explored the dyadic nature of attachment patterns within the therapeutic process although findings are inconclusive. Objective: The current study aimed to extend previous empirical evidence by exploring the application of attachment theory within a naturalistic clinical setting. Both patient and therapist attachment patterns were considered individually and as a therapeutic attachment dyad in relation to clinical outcomes following psychological therapy. It was hypothesised that patients reporting higher levels of attachment anxiety and avoidance would experience greater levels of psychological distress, less symptomatic relief and greater difficulty engaging with therapy. It was also hypothesised that patient and therapist attachment patterns would interact to moderate the trajectory of psychological therapy. A secondary aim of the study was to test the relationship between attachment dimensions and dispositional coping style within a clinical psychology population. A systematic review of the literature exploring attachment patterns and coping styles was also conducted. Results: Findings of the systematic review were suggestive of a relationship between attachment style and coping style that were consistent with theoretically derived assumptions. The results of the current empirical study lend support to the role of individual attachment patterns in coping and clinical outcomes, as well supporting the idea that therapist attachment can affect clinical outcomes through therapeutic engagement. Conclusion: The clinical application of attachment theory provides an interesting perspective on how services can best adapt to meet those most in need, although further research is required.