Campaigns aiming to encourage people to reduce their energy consumption frequently make three well-intentioned but inadvertent mistakes in their communications strategies. These mistakes are driven by a deeply embedded yet often counterproductive popular intuition: that ‘more is better.’ We identify three messaging pitfalls that can result from this assumption, namely that a message will be more persuasive if it emphasizes the greatest number of people engaging in undesirable behavior, the greatest number of victims of such behavior, and the greatest number of reasons why one should adopt particular energy conservation and efficiency measures. We cite experimental evidence demonstrating that these strategies can in fact reduce the persuasive power of a message, and review several underlying psychological mechanisms that may explain these counterproductive effects. Finally, we provide a number of alternative messaging strategies that are likely to improve the performance of energy conservation campaigns.