Background: Unintentional injury has been the leading cause of death for children and teenagers in the United States for the past 2 decades. Its health outcomes are often studied, but it may also relate to psychological concepts such as emotion dysregulation, which may also result in severe outcomes for individuals, families, and societies. There is no consensus on a conceptual definition of emotion dysregulation, and little prior literature on the specific relation between dysregulation and injury in the transition to adolescence. Methods: The current study aims to identify latent factors of emotion dysregulation using exploratory factor analyses. Subsequently, multilevel regressions illuminate relations between dysregulation and injury at 2 late childhood and early adolescence time points in a large ethnically, socioeconomically, and regionally representative sample of Arizona twins recruited from birth records and ongoing efforts. Results: 6 total factors representing emotion dysregulation at 2 ages were created. Factors were valid when tested against temperament and psychopathology constructs. No significant longitudinal or cross-sectional associations between emotion dysregulation factors and unintentional injury were found. Sex and rurality differences were found in factor scores and dysregulation outcomes. Discussion: The current study highlights new avenues of research and funding. Future research on this topic should reflect a concentrated and nuanced focus on injury. Concordant age 9 and age 11 factors loaded differently, which urges the field to strive toward developing a standardized definition for emotion dysregulation. Covariate differences highlight target populations for interventions in unintentional injury and emotion dysregulation, which remain independent areas of concern.