Objective and method: Company size is a proxy for other variables affecting occupational health and safety (OHS) performance. The aim of this literature study was twofold: to give an overview on how it empirically has been shown that smaller and larger companies differ from one another in terms of OHS, and to present how earlier studies have defined company size when studying its mediating effects on OHS. A search strategy with search terms was used in the major databases, as well as inspecting the reference list of appropriate studies recovered. A total of 29 articles were included.

Findings: Examining what empirically has been shown on company size differences in terms of OHS resulted in ten different themes. For example that the OHS standard improves as company size increases, that there is an inverse relationship between company size and injury frequency, and that the rate of absenteeism is lower in small companies. The examined studies were similar, in that they found differences attributed to company size. They differed, however, in the ways they defined company size as a variable in analysis. To define company size as number of employees was the most commonly used approach (27 out of 29 studies). One study used number of man-labor years as definition. One study used the contractors’ annual volume of business in dollars as definition. The scale of measure that was most commonly used as variable for measuring company size was ordinal scale data (23 out of 29 studies). Three studies used ratio scale data. Three studies did not specify scale of measurement.

Conclusion: It is important to carefully consider what definition and scale of measure to use for the sake of studying the mediating effects of company size on OHS. Some of the less commonly used alternatives could be relevant.