Individuals are increasingly being urged to 'do their bit' in the fight against climate change, with governments and pro-environmentalists insisting that the collective impact of small behaviour changes will result in a meaningful reduction in global carbon emissions. The following paper considers this debate, as well as offering personal contributions from two leading environmentalists: Dr Doug McKenzie-Mohr, environmental psychologist and author of Fostering Sustainable Behavior: Community-Based Social Marketing; and Dr Tom Crompton, change strategist for WWF and co-author of Meeting Environmental Challenges: The Role of Human Identity, who argues for the role of intrinsic value systems in achieving sustainable behaviour change. As well as considering the responsibility of the individual in mitigating climate change, the paper introduces the discipline of social marketing as an effective tool for facilitating individual behaviour change, drawing on evidence from the field to recommend the key characteristics of effective behaviour change programmes.