We extend recent critiques of research on generations in the work context by proposing a differentiated lifespan developmental perspective. We accomplish this through several means: First, we define generations and trace the historical development of this concept from sociological thought experiments to their contemporary (mis) use for understanding individual-level psychological processes at work. Second, we review core principles of the lifespan developmental perspective, with an emphasis on contextual-dialectical models of human development. Third, we argue that generations are better understood from a contextualized lifespan framework that accounts for time period and history-graded developmental influences that may impact individuals' attitudes, values, beliefs, motives, and behavior at work. Fourth, we propose a new lifespan model of generations and offer several associated propositions to serve as a theoretical guide as well as an agenda for future research. Finally, we review and critique methodologies typically used to study generational effects, outline methodological recommendations to guide future studies, and offer practical recommendations based on our model. Overall, this article contributes to better theorizing and more rigorous research and practice regarding the idea of generations at work.