Abstract
Many Occupational Safety and Health (OSH) interventions have proven to be effective only under controlled conditions; during the implementation in practice, the interventions may not work as expected, especially in small and medium-sized enterprises (SMEs). SMEs are affected by different contextual factors than larger enterprises and these factors can influence the outcome of the OSH programs. Three different phases of an OSH intervention (design, implementation, and control) have been considered. The aim of this research is to understand what are the mechanisms by which an OSH intervention works or does not work as expected, together with barriers and drivers, and the related contextual factors. The research was designed following multiple case study research, which enables an in depth understanding of the intervention process and the identification of the most relevant factors for OSH. Data were collected through interviews with owner-managers or OSH managers of SMEs. Finally, the data were analysed through an analytical research framework that enabled the identification of the main mechanisms and contextual factors for the interventions that had an expected outcome and for those which had an unexpected outcome.