Psoriasis is a chronic skin condition that can impair physical, psychological and social functioning. A sub-population of people living with psoriasis believe that psychological stress exacerbates their physical symptoms. Stress may exacerbate psoriasis via a psychoneuroimmunological pathway. The cortisol awakening response can be used to indicate whether this pathway is functional or dysfunctional. People with psoriasis have an elevated risk of emotional distress (anxiety and depression) and an impaired quality of life. Mindfulness based cognitive therapy has been effective in reducing stress, emotional distress, quality of life impairment as well as improving physical health. The aim of this thesis is to examine the efficacy and acceptability of mindfulness-based intervention for people living with psoriasis and whether the cortisol awakening response mediates the relationship between perceived stress and physical severity of psoriasis. This thesis adopted a mixed-methods design. A pilot, randomised control trial examined the effects of mindfulness based cognitive therapy upon the physical severity, perceived stress, emotional distress, quality of life and cortisol awakening response of people living with psoriasis. These variables were entered into a correlation analysis to examine whether the cortisol awakening response was associated with any of the reported study outcomes (physical severity, perceived stress, emotional distress and quality of life). Completers of the mindfulness intervention were invited to a semi-structured interview to explore the characteristics of the participants who adhered to the intervention and their experiences of participating. The mindfulness intervention significantly improved physical (z=1.96, p=0.05) and quality of life (z=2.30, p=0.02) measurements without changing perceived stress (z=0.07, p=0.94), emotional distress (z=1.60, p=0.12) or cortisol awakening responses (z=-0.33, p=0.74). The overall cortisol awakening response was not associated with physical severity (r=-0.30, p=0.07) or perceived stress (r=-0.20, p=0.25) but was significantly correlated with emotional distress (r=-0.35, p=0.04). The intervention was perceived as an acceptable adjunct treatment option. Participants reported some process barriers that inhibited their learning of mindfulness skills. A profile emerged that described a sub-population of people with psoriasis. This sub-population may be more likely to accept and adhere to mindfulness based cognitive therapy.This thesis provides preliminary support to the concept that increasing mindfulness skill can reduce the physical severity and quality of life impairment in people with psoriasis. It recommends that a fully powered trial be conducted to examine the effectiveness of mindfulness in improving physical and overall functioning for people with psoriasis. This thesis suggests clinicians screen their patients and offer a psychological intervention best suited to their needs and characteristics.