Energy is often viewed as the basic fuel for individual action and cognition, yet what exactly is energy? How can it be defined? How should it be measured? And, most importantly, why should organizational scholars, especially positive organization scholarship (POS) scholars, care about it? This chapter reviews the burgeoning interdisciplinary literature on energy-related constructs. We identify six distinct streams of energy-related literature. We then highlight how human energy at work can contribute to our understanding of POS.