Generation Z (1997-2012) has been characterized in the popular media as more socially inhibited, cautious, and risk averse than prior generations, but are these differences found between generations on an empirical level? And, if so, are these differences observable within generations in response to acute events such as the COVID-19 pandemic? Using a simplified time-lagged design to control for age effects, we examined between-group differences in self-reported shyness in young adult participants (N = 806, age: 17-25 years) at the same developmental age and university from the millennial generation (tested: 1999-2001; n = 266, Mage = 19.67 years, 72.9% female) and Generation Z (tested: 2018-2020), the latter generation stratified into prepandemic (n = 263, M = 18.86 years, 82.4% female) and midpandemic (n = 277, Mage = 18.67 years, 79.6% female) groups. After first establishing measurement invariance to ensure trustworthy group comparisons, we found significantly higher mean levels of shyness across each successive cohort, starting with millennials, through Generation Z before the pandemic, to Generation Z during the pandemic.