Serious pathology accounts for only 1 per cent of back pain in the general population, however, if you work within musculoskeletal medicine, at some stage, you will see a patient with serious pathology. Red Flags is the essential guide to correctly identifying and acting on warning signs when a therapist becomes suspicious of serious pathology in a patient presenting with back pain. This handy pocketbook offers practical strategies for developing clinical reasoning so that therapists are able to distinguish between Red Flags and Red Herrings along the patient journey, and have greater confidence in their diagnosis. Drawing on their years of experience and personal case studies, Greenhalgh and Selfe, present a truly innovative guide. They introduce: a hierarchy of Red Flags; an 'Index of Suspicion'; thoughts on Red Herrings; a model of 3D thinking; and, the consideration of conditional probabilities. Log-on to the associated website to gain free access to a downloadable wall chart of the Red Flag Hierarchy and the authors' Physiotherapy journal articles.