Accumulating research suggests that the adoption of high performance work practices (HPWPs) is related to organizations' performance. The evidence base is limited by its reliance on retrospective survey reports. This study uses an intervention, including longitudinal interview and survey reports, of the implementation and outcomes of the introduction of HPWPs alongside time series data of objective performance metrics recorded before and after the intervention. The results showed that the implementation of HPWPs was associated with subsequent and sustained increases in productivity and safety performance. The study suggests that a specifically designed intervention involving HPWPs can have beneficial effects both on productivity and safety, but other intermediary variables associated with the implementation process may be critical in mitigating potentially detrimental worker welfare effects arising from work intensification.