This study examined longitudinal and concurrent relations between temperament, ability estimation, and injury proneness. Longitudinal assessments of Inhibitory Control were collected through a behavioral battery at toddler (33 months) and preschool ages (46 months). Parent-reported measures of Inhibitory Control and Extraversion also were obtained at those ages. At school age (76 months), children participated in a set of tasks to assess overestimation and underestimation of physical abilities. Parents provided reports of children's temperament and injury history at school age. Results showed that children who were high on Extraversion and low on Inhibitory Control as toddlers and preschoolers tended to overestimate their physical abilities and to have more unintentional injuries at age 6. Children low on Extraversion and high on Inhibitory Control tended to underestimate their physical abilities. Implications for injury prevention are discussed.