It was found that Urgency and lack of Perseverance were significantly elevated in women with self-injury or eating pathology, and significantly higher again in women with both these syndromes. A longitudinal design found that self-injury tends to progress from milder, compulsive forms, to more severe, impulsive forms over time. The portfolio examines the frequent co-occurrence of substance use and psychiatric disorders (Dual Diagnosis). Four primary conceptualisations of how dual diagnoses develop and present are discussed. These models are then applied to inform four case studies.