1 THE WHEN AND HOW OF COMMUNICATING CLIMATE CHANGE CAROLINE WILSON KATHERINE N. IRVINE GREIG MILL cwilson@dmu.ac.uk De Montfort University (United Kingdom) ABSTRACT This investigation discovers how combined use of the Theory of Planned Behaviour and the Elaboration Likelihood Model could offer greater specification for both academics and practitioners looking to improve the effectiveness of communication as a tool to encourage behaviour change. It will contribute, as Stern called for, to greater understanding of the catalogue of variables which are involved when people are contemplating changing environmentally significant behaviours. KEY WORDS Elaboration Likelihood, Planned Behaviour, Communication, Climate Change