Abstract: The relationship between scientific knowledge and decision-making surrounding environmental issues is complex and represents a flourishing area of scholarship and practice. However, a sense of frustration persists regarding efforts to increase the use of science for decision-making. Regulations of copper smelter arsenic emissions developed in Chile during the 1990s represent a successful example of science informing policy making. The case involved production and use of local science in contrast to the common practice of copying international ambient standards. In this paper, we investigate arsenic regulation in Chile in the 1990s and focus on the role of the major science intervention during the process, project FONDEF 2-24. The case is examined through the lens of knowledge governance (van Kerkhoff and Pilbeam, 2017). This theoretically-oriented approach guides our critical reflection on the relationship between knowledge and policy making, taking into consideration the formal and informal rules that shape the intervention and the underlying social and cultural patterns. The success of the science intervention's influence on policy is better understood with such a perspective. We expand the knowledge governance approach by scrutinizing the relations of coherence between levels of analysis to assess their alignment. The approach could be helpful for studying other cases, particularly at times when a new field of policy is emerging.