There is a growing recognition of the need for frameworks for environmental management which transcend disciplinary boundaries while building upon established approaches to applied research which have recognized legitimacy and utility. This paper investigates ways of thinking about practical transdisciplinarity in cases of integrated environmental and landscape management. A brief review is first presented of systemic conceptions which can inform our transdisciplinary practice, including ‘civic science’ and a recognition of contestable concepts. This is followed by a discussion of current approaches to inquiry and management of lived‐in environments and landscapes, particularly that of integrated catchment management (ICM). Three case studies at different scales are then described to highlight the importance of core ‘contestable concepts’ around which transdisciplinary dialogues can occur. The first case study is that of the question of ‘risk’ in relation to the Hawkesbury Water Reuse Scheme, on the Hawkesbury campus of the University of Western Sydney. The second case study is that of ‘investment’ in stormwater and wastewater management in the Hawkesbury–Nepean River Catchment, in Western Sydney. The third case study is of the question of ‘meta‐methodology’ when developing cases of ICM in China which build on both international experiences and the local context. The final section engages with transdisciplinarity as a contestable concept itself. The breadth of fields of inquiry engaging with this notion are briefly identified, along with some key examples of emerging concepts and language which may be broadly applicable to cases of environmental and landscape management. Copyright © 2005 John Wiley & Sons, Ltd.