The ability to learn new concepts involves linking pieces of related information to create an organized knowledge structure, and it is an essential cognitive function for individuals of all ages. Despite its importance, concept learning has received less attention in the field of cognitive aging compared to areas such as episodic memory and cognitive control, and there has yet to be a synthesis of age-related findings in this domain. In this review, we summarize the findings from empirical studies investigating age-related differences in categorization-a domain within concept learning that involves linking items to a shared label and allows for classification of novel members of the category. We focus on several hypotheses about what might drive age-related differences in categorization, including differences in perceptual clustering, the ability to form specific and generalized category representations, performance on tasks that are thought to recruit different memory systems, attention to stimulus features, and strategic and metacognitive processes. Overall, the existing literature suggests that older and younger adults may differ in the way they approach learning new categories, and this difference emerges across several different categorization tasks and category structures. We conclude by encouraging future research that takes advantage of the strong existing theoretical foundations in both the concept learning and cognitive aging domains. This approach has the potential to broaden our understanding of the factors that influence category formation across the adult lifespan and provide a more complete picture of age-related differences across multiple cognitive domains. (PsycInfo Database Record (c) 2023 APA, all rights reserved).