Relatively few studies have longitudinally investigated how COVID-19 has disrupted the lives and health of youth beyond the first year of the pandemic. This may be because longitudinal researchers face complex challenges in figuring out how to code time, account for changes in COVID-19 spread, and model longitudinal COVID-19-related trajectories across environmental contexts. This manuscript considers each of these three methodological issues by modeling trajectories of COVID-19 disruption in 1080 youth from 12 cultural groups in nine nations between March 2020-July 2022 using multilevel modeling. Our findings suggest that for studies that attempt to examine cross-cultural longitudinal trajectories during COVID-19, starting such trajectories on March 11, 2020, measuring disruption along 6-month time intervals, capturing COVID-19 spread using death rates and the COVID-19 Health and Containment Index scores, and using modeling methods that combine etic and emic approaches are each especially useful. In offering these suggestions, we hope to start methodological dialogues among longitudinal researchers that ultimately result in the proliferation of research on the longitudinal impacts of COVID-19 that the world so badly needs.