Little is known about the psychological stress and secondary impacts emerging among the general U.S. population as a result of the ongoing COVID-19 pandemic. The purpose for the current study is to assess the prevalence rates of Generalized Anxiety Disorder (GAD) and to establish psychosocial correlates, pandemic-themed concerns, and other comorbidities for those with GAD at the initial onset of the COVID-19 pandemic. This online study included 2,101 U.S. adults between April 14-22, 2020, during the initial stay-at-home protocols and assessed GAD, psychosocial factors, and pandemic-related factors including concerns, changes in health behaviors, and adherence to protocols. The results demonstrated a high prevalence rate (17.9%) for GAD during the initial COVID-19 outbreak compared with the prior 1.8% 12-month estimate before the pandemic. Individuals with GAD reported significantly higher levels of stress, loneliness, fatigue, and empathic concern, along with reductions in levels of quality of life. Likewise, those with GAD reported significantly higher pandemic-related concerns, poorer changes in general health behaviors, and less confidence in the government's response to the pandemic. For clinical purposes, these findings provide insight into the various types of pandemic-themed worries that individuals meeting clinical criteria for GAD will have the most difficulties controlling.