Previous research has identified an association between attachment orientations and depression and anxiety. Unfortunately, the majority of this work is correlational and we do not know if there is a causal relationship between having an insecure attachment style and affective disorders or vice versa. The first aim of this research was to fill this gap and review the literature that addresses the role of primed attachment security on depression and anxiety in a clinical sample. Twenty-four empirical studies met inclusion criteria. Although limited, evidence is emerging that supports the benefits of secure priming for improving affective disorders. However, limitations of existing literature including sample characteristics, type of priming method and the variability of outcome measures make generalisation of findings difficult. The second aim of this research was to expand the existing knowledge-base by testing the effectiveness of secure attachment priming on a clinical sample of patients diagnosed with depression and/or anxiety disorders. Fifty-two participants engaged in secure attachment priming or neutral priming in the laboratory (Time 1), after which they received three daily consecutive primes according to their experimental condition (Times 2-4), aimed at maintaining the effects from Time 1 priming. A follow-up one day later (Time 5) was also included. Participants in the secure priming condition experienced higher felt-security following the initial prime and at all time-points than the control group, indicating that the felt security benefit was maintained across a number of days through repeated priming. Secure priming also had a beneficial impact on reducing the symptoms of anxiety and depression in comparison to the control prime though the differences between the groups were only significant at Time 4. This experiment was the first to use repeated security priming with a clinical sample and findings contribute towards the understanding of attachment processes and affective disorders.