In this review of a range of studies on the health and safety effects of precarious employment in industrialized societies published since 1984, the authors examine the overall findings and methodological issues and identify areas in need of further research. Of the 93 published journal articles and monographs/book chapters reviewed, 76 studies found precarious employment was associated with a deterioration in occupational health and safety (OHS) in terms of injury rates, disease risk, hazard exposures, or worker (and manager) knowledge of OHS and regulatory responsibilities. Of the more than 25 studies each on outsourcing and organizational restructuring/downsizing, well over 90 percent find a negative association with OHS. The evidence is fairly persuasive for temporary workers, with 14 of 24 studies finding a negative association with OHS. The evidence is less strong for small business, and a handful of studies on part-time workers found no clear association with negative OHS outcomes (in some cases the reverse). Further research is needed to more clearly link health effects to particular business practices and neoliberal policies and to explore the regulatory implications of the growth of precarious employment. The authors suggest some ways to conceptualize the association between precarious employment and occupational health.