Though gratitude research in organizational behavior (OB) is nascent, this emotion has a rich history in the social sciences. Research has shown gratitude to promote prosocial behaviors, encourage personal well-being, and foster interpersonal relationships. However, gratitude research has been siloed among these three outcomes of gratitude (moral, wellness, and relational). Similarly, past reviews of gratitude have focused on only one group of outcomes, one of its forms (trait, state, or expressed), or empirical findings without emphasis on the theoretical underpinnings. In contrast, this review recognizes that each type of gratitude, its functions, and outcomes are part of a single process model of gratitude. As such, in the current review, we provide a comprehensive assessment of gratitude in the social sciences by distilling and organizing the literature per our process model of episodic gratitude. Then, we translate the insights for management scholars, highlighting possible differences and synergies between extant research and workplace gratitude thereby helping advance "gratitude science" in the workplace. In all, this review (a) examines definitions and operationalizations of gratitude and provides recommendations for organizational research; (b) proposes a process model of episodic workplace gratitude as a conceptual map to guide future OB research on gratitude; (c) reviews empirical gratitude research through the lens of our process model; and (d) discusses the current state of the literature, important differences for workplace gratitude, and future directions for organizational scholars.