Integration and integrated approaches are increasingly presented as new and superior ways to consider the environment in policy-and decision-making. If used in an uncritical way, this assertion could become a hindrance to good practice and could undermine efforts to defend or improve environmental quality. The aim of this paper is to provide the missing critical perspective through an investigation of the meanings of integration found in recent literature on assessment. This literature represents a broad survey of European (particularly UK) and US critiques of assessment practices, and proposals for better and usually 'more integrated' approaches. These critiques and proposals relate to a range of assessment contexts, from relatively technical issues of data handling, to questions of the design, choice and implementation of policy options. This paper also surveys, and contributes to, literature that questions the central goals and assumptions informing assessment practice and environmental governance more widely. Fourteen meanings of 'integration' are presented, with a discussion of the potential synergies and conflicts among them, and with environmental objectives. Integration is argued to be a matter of value judgements concerning assessment design in specific historical and social contexts. Far from providing a panacea, integration would appear to create as many challenges as it might resolve in seeking to achieve more sustainable development.