This article examines three significant and increasingly important public policy issues: OHS, harmonisation and evaluation. OHS is an issue on which comparatively little has been written in public administration, yet it is an issue from which much can be learned–especially about the intersection between social and economic policy. In this regard, the harmonisation of Australia’s OHS laws provides a valuable opportunity to evaluate and better understand the benefits and costs of the harmonisation of social regulation in the name of economic efficiency. Such an evaluation is inevitably challenging, with the already difficult job of evaluation complicated by a multiplicity of stakeholders and objectives. This article examines the challenges which these multiple objectives held by multiple stakeholders present for evaluation. In doing so, it demonstrates that far from being interpreted simply as difficulties to be overcome, they actually represent an opportunity to enhance both the legitimacy of the evaluation process and the utility of its outcomes.