Lean management and related ideas have had a significant impact on organizations throughout North America and the world. Despite its popularity and impact, I-O psychologists have largely neglected Lean as a research topic and few I-O psychologists engage in applied practice in the area. In this focal article, we provide a working definition of Lean and present examples of Lean’s influence. Next, we outline possible reasons to explain I-O psychologists’ indifference to Lean. Finally, we provide some topic areas that I-O psychologists can use to contribute to the Lean literature. By using I-O psychologists’ skill in measurement and evaluation, along with our considerable organizational theory, we believe that I-O psychology can improve Lean and broaden their impact. We hope this focal article will inspire I-O psychologists to reconsider a research and practice area that they have previously ignored. In addition, we hope that this article causes I-O psychologists to reflect on their role to play in addressing popular management trends.