There is a growing understanding that modern slavery is a phenomenon ‘hidden in plain sight’ in the home countries of multinational firms. Yet, business scholarship on modern slavery has so far focussed on product supply chains. To address this, we direct attention to the various institutional pressures on the UK construction industry, and managers of firms within it, around modern slavery risk for on-site labour. Based on a unique data set of 30 in-depth interviews with construction firm managers and directors, we identify two institutional logics as being integral to explaining how these companies have responded to the Modern Slavery Act: a market logic and a state logic. While the institutional logics literature largely assumes that institutional complexity will lead to a conciliation of multiple logics, we find both complementarity and continued conflict in the logics in our study. Though we identify conciliation between aspects of the market logic and the state logic, conflict remains as engagement with actions which could potentially address modern slavery is limited by the trade-offs between the two logics.