This paper discusses several possible 'idealised' functional relationships between environmental and economic performance rooted in different theoretical frameworks. Following this, it reviews empirical studies that investigate this relationship and it analyses their results. This is done separately for event studies, portfolio studies and multiple regression studies, with particular regard to the data sets used, the environmental performance measures applied and the economic performance measures utilised, including data sources for the latter two study types. Subsequently, the paper discusses the consistency and comparability of empirical findings and their link to the theoretically derived 'idealised' functional relationships. It then compares theoretical propositions and empirical results and, in doing so, identifies a number of statistical, methodological and data issues. The paper concludes by commenting on these, in particular on the variability encountered, and assesses potential initiating factors for the relationship that could account for this variability. It closes with a brief discussion of potential future research paths and difficulties that could be encountered on these, particularly with regard to European firms.