This paper presents an analysis of how the particular categories of children and youth are used within the instructional work of learning to drive. Using Membership Categorisation Analysis (MCA) and multimodal Conversation Analysis (CA) of a collection of cases drawn from 85 video-recorded driving lessons, we demonstrate how the participants treat children and youth as a category of traffic users whose main category predicate appears to be their expected unpredictability and carelessness, placing particularly high demands on drivers’ awareness and caution. This is evident in in-event and post-event interactions about traffic encounters with children and youth, as well as in traffic contexts where they have not (yet) been spotted but their sudden appearance is anticipated. The results suggest that the institutional constructions of children and youth as a potential source of trouble prepare trainee drivers for unforeseen events and contingencies and shape their social stock of knowledge as future motorists.