This paper contains a consideration of the recent arguments in favour of adopting 'anticipate and prevent' or 'proactive' energy - environment policy strategies, in place of the 'reactive' strategies that are a feature of many current approaches to policymaking in this area. The roles that energy - environment modelling might play in investigating alternative scenarios and proactive policy strategies are then examined. The focus is on the advantages and disadvantages of using input - output analysis and related mathematical programming techniques to provide information for the policymaking process. Of course, input - output analysis is neither the only nor the ideal approach to energy - environment modelbuilding. However, despite acknowledged conceptual and practical limitations of applying input - output analysis in this area, it is suggested there is a case for considering its further application, particularly in the context of the United Kingdom, not least because it enables a general equilibrium approach to be implemented.