The aim of this research is two fold: (a) to inquire into the methodological foundations of boundary setting for improved sustainability reporting and (b) to explore current corporate practice in this area, with a particular emphasis on environmental indicators. The paper contends that the boundaries of significant sustainability indicators should encompass all entities over which there is sustainability control, together with indirect impacts arising from activities across the supply chain, and not merely direct impacts caused by entities within boundaries based on financial control. The paper explores, through an empirical study of the sustainability reports disclosed by some of the top FT500 companies, how corporations are setting environmental boundaries in practice. Results show a lack of ambition in the practice of setting organizational and operational boundaries. Most reporting entities define organizational boundaries restricted to financial control, and most of the indirect environmental impacts sought remain undisclosed