The public's fear of COVID-19 may cause severe consequences. The current project explored what caused U.S. adults' fear of COVID-19 and how they regulated fear using a longitudinal two-wave survey on a national-representative sample (N = 315). Results showed that participants' media exposure frequency and their perceived valence of interpersonal communication predicted their fear of COVID-19 at both waves, and fear at wave 1 further motivated higher frequency of media and interpersonal communication as well as strengthened perceptions that their interpersonal conversations emphasized the danger aspect of COVID-19 at wave 2. Counterarguing was effective in down-regulating individuals' fear, which in turn further encouraged more subsequent use of such strategy. Avoidance used in wave 1 predicted counterarguing at wave 2, while counterarguing employed in wave 1 predicted the subsequent use of reappraisal. Individuals may choose to use counterarguing as a maladaptive coping strategy to control their fear, and they tend to shift from one emotion regulation strategy to another as the pandemic progresses.