Household norms have been shown to influence energy efficiency behaviors, but little is known about the relative influence of household norms when compared to other established drivers of household efficiency behaviors, such as comfort-seeking, environmental concern and cost sensitivity. This paper unpacks the nature of the influence of household norms on household efficiency behaviors, whether as antecedents, mediating the influence of other drivers or a direct influence on efficiency behaviors. Responses from 775 households in regional Australia were analyzed to test six hypotheses. Results suggest that household norms are among the most important variables influencing household efficiency behaviors. They have a strong and significant influence on curtailment and investment behaviors, mediate the relationship between established drivers of efficiency and efficiency behaviors and influence the drivers of efficiency. These findings demonstrate the importance of household norms for improving the energy efficiency of households.