The initial clinical assessment of spinal pain consists of diagnostic triage into: (i) serious spinal pathology; (ii) other pathological entities; and (iii) non-specific symptoms. The non-specific group comprises the major burden of spinal illness. There are two broad approaches to the diagnostic challenge of non-specific spinal pain. One approach is to split the group into sub-groups explained by separate pathophysiological abnormalities. The focus of this work is to describe these proposed abnormalities in greater detail and to discover which clinical features distinguish them. The other approach is to 'lump' all of those with non-specific features into one group, and consider the common psychosocial factors that are relevant to the whole group. A variety of pathological and non-pathological models have been proposed. Pathological models include ligament laxity, facet syndrome, discogenic pain, spondylosis and instability; non-pathological models include a pain-spasm-pain cycle, muscle inhibition and deconditioning and somatic dysfunction. All of these models are problematic and do not fully account for all of non-specific spinal pain. Another approach is to consider these two different approaches together and to consider this non-specific category as orthogonal dimensions of pathology and dysfunction.