The aim of this study was to construct novel indices to indicate, in a quantitative manner, the relationship between students’ willingness to undertake specific pro-environmental actions and their belief in the usefulness of those particular actions in the context of global warming. A questionnaire was used to determine the views of 1444 Greek secondary school students. For some actions (for example, recycling and switching off un-used electrical items) the extent to which students professed a willingness to act was greater than might be expected from the degree to which they believed the action would be useful. For other actions (for example, using public rather than private transport or buying smaller cars) the degree to which students were willing to act seemed less than might be expected, given their belief in the usefulness of the action. The data also provided an indication of the potential effectiveness of education about different actions. For some actions, such as issues about consumerism, this relationship was weak; here, even if people could be persuaded of the usefulness of the action, they might not make changes in their behaviour. For issues such as these, other inducements may be needed to persuade people to adopt pro-environmental behaviours. For other actions, such as economising on the use of electricity in the home, the relationship was stronger; in these areas environmental education could well be effective.