Let us move forward: Comment on "are generations a useful concept?".

Generational labels (e.g., Millennials and Baby Boomers) are widely used in daily life to represent the unique characteristics of groups of people. However, the existence of generational differences remains contentious. In their focal paper, Costanza et al. (2023) critically reviewed the literature on generational differences and proposed two future research directions: the social constructionist and lifespan development perspectives. In this commentary, we aimed to extend the proposed directions for future research on generational differences by integrating the two perspectives into one theoretical framework. Future research should investigate how proximal social relationships (e.g., intergenerational relations) and distal social norms (e.g., age norms) change over historical time and whether these historical changes shape individuals' development and aging. The theoretical framework that integrates the two proposed research directions may stimulate research on generational differences to progress beyond the concept of generations.