Professor Horne’s research focuses on the role of psychological and behavioural factors in explaining variation in response to treatment. He has developed a range of tools and models for assessing patient perspectives of illness and treatment (e.g. the Beliefs about Medicines Questionnaire [BMQ] and the Medication Adherence Report Scale [MARS] and frameworks (a Necessity-Concerns Framework) for understanding treatment-related behaviours with a particular focus on adherence to medication. This work translates into a portfolio of theory-based pragmatic interventions to help patients get the best from treatments by supporting optimal adherence and self-management. Studies are ongoing in a range of long term conditions including asthma, COPD, diabetes, cardiovascular disease, kidney disease, HIV, inflammatory bowel disease, rheumatologic disease, bipolar disorder and cancer. Professor Horne’s work extends into broader aspects of health and illness such as the placebo/nocebo effect and the role of language, emotion and emotional disclosure in illness related behaviours and outcomes.