A wide range of individual, interpersonal and environmental factors influence the safety of pedestrians crossing the street, including human development (children take more risks than adolescents and adults) and sensation seeking (individuals higher in sensation seeking have greater risk). The interaction between those two variables has not been carefully studied, however. Does the effect of sensation seeking on pedestrian safety vary across human development as cognitive and other skills improve? This study investigated the primary effects of age and sensation seeking, plus their joint effects, on pedestrian crossing in a virtual reality environment. 209 children (10–13 years old), adolescents (14–18 years old) and young adults (20–24 years old) screened to be high and low level in sensation seeking participated. A 3 (age group: child vs adolescent vs young adult) × 2 (sensation seeking: high vs low) × 2 (traffic condition: easy vs harder crossing) mixed factorial design was conducted. Three pedestrian safety outcomes – start delay, missed opportunities and dangerous crossings – were considered. Results showed that when the traffic condition was easier to cross within, the start delay to enter traffic gaps was significantly shorter for children than for adolescents and young adults. There were no significant differences across age groups when the traffic condition was harder to cross within. Pedestrians also missed more opportunities to cross the road when the traffic condition was harder to cross within. Pedestrians low in sensation seeking missed more opportunities to cross than those high in sensation seeking. All age groups had more dangerous crossings during the harder crossing scenario than in the easier one, and adolescents had more dangerous crossings than young adults or children. Finally, the results of hierarchical regression models predicting dangerous crossings showed that traffic condition had a significant predictive effect on children's dangerous crossing behavior, and both high sensation seeking...