Although trajectories of youth volunteering were disrupted by the COVID-19 pandemic, nevertheless some youth persisted in volunteering, and others emerged as volunteers. To understand volunteering trajectories, the present mixed method study proposed a model adapted from prior literature and examined volunteer trajectories during the pandemic. Youths' volunteer trajectories were categorized (as persistent, emergent, or former volunteer, or persistent non-volunteer), and their justifications for their volunteer decisions were classified using social domain theory (personal, social, moral, and prudential). A sample of 461 youth (M[subscript age] = 19.26; 68.8% female; 41.6% European or North American) from a large Canadian university completed a retrospective survey on pandemic volunteering and volunteer decisions. Volunteer decisions were coded using conventional and directed qualitative content analysis. Although the pandemic disrupted the volunteering trajectories of former volunteers, overall, more youth persisted or emerged as volunteers during the pandemic, a finding framed in both the trajectory and emergency and disaster literature. Volunteers were more likely to use "moral" justifications, whereas "prudential" justifications were more frequent among non-volunteers. The present study offers insight into the impact of the pandemic on youth volunteering and is one of the first studies to find a substantive role for prudential reasoning in youth decision making.