Conserving water and energy is a key policy goal in many countries. Campaigns that address consumer behavior have been shown to be a cost-effective and powerful measure to attain this goal. However, little is known about the psychological mechanisms driving these changes in behavior. In this context, we perform a randomized controlled trial with 697 households to evaluate the effectiveness of providing real-time information about personal water and energy consumption in the shower. During a 2-month intervention, we observe a sustained reduction in resource consumption with an effect size of over 20%. In combination with detailed survey data on demographics and personality traits, we are able to assess a comprehensive set of psychological mechanisms and their interplay behind the behavioral responses observed, which is key for the welfare analysis of policy interventions. Joint with Verena Tiefenbeck, Kathrin Degen, Vojkan Tasica, Rafael Lalive, Elgar Fleisch, and Thorsten Staake.