Despite the prevalence of research on the consequences of collective turnover (TO), we lack an understanding of how, when, and why changes in the external environment influence collective turnover. The present study extends context emergent turnover and threat-rigidity theories to consider temporal changes in rates of collective turnover brought on by an external disruption. We also conduct variance decomposition to evaluate the relative influence of internal and external factors on collective turnover and examine how changes in the external environment impact relative influences. Finally, we examine the role of collective engagement in explaining patterns of collective turnover over time. Our study is based on a large, geographically dispersed U.S. firm. Findings from a two-phase longitudinal model reveal that rates of collective turnover change over time in ways that are predictable from threat-rigidity theory. Variance decomposition analysis finds that internal store-level factors explain substantially more variance than external factors, but the balance changes in response to an external disruption. We also show that collective engagement can mitigate increases in collective turnover. Results inform theory regarding the relative importance of internal versus external factors in influencing collective turnover and provide a framework for predicting how contextual change in the external environment impacts collective turnover over time. (PsycInfo Database Record (c) 2024 APA, all rights reserved).