Individual factors have been variously defined as non-work, demographic, physiological or psychological factors. They may represent a variety of important constructs at different relevant levels that may not be initially evident in their measurement. These include: work-related factors e.g., job assignment, duration of exposure, work style, anthropometric mismatches, and differential responses to job demands; concomitant external or internal exposures e.g., sports, smoking, and endogenous hormones; and physical, psychological and social vulnerabilities e.g., prior injury, depression, socio-economic status. Such factors operate in different ways in the development, course and response to interventions of musculoskeletal disorders. Newer framings of their contribution to musculoskeletal disorders are providing new insights into the role of such factors as some among many which contribute to the burden of MSK disorders in working age populations. As researchers, practitioners and policy makers, we need to consider them in order to reduce burden, to protect the vulnerable and to match interventions to different groups of people most appropriately.