ABSTRACT Objective We designed The Irritability and Dysregulation of Emotion Scale (TIDES-13) to test whether irritability consisted of several sub-dimensions that would correlate differentially with internalizing/externalizing psychopathology, age, and gender. Method Parent-report (n = 3935, mean age = 8.9) and youth self-report (n = 579, mean age = 15.1) versions of TIDES-13 were administered to a population-based sample. Exploratory and confirmatory factor analyses were conducted on separate sub-samples. We fit multivariable regression models between TIDES-13 sub-dimensions and age, gender, anxiety, depression, ODD and ADHD trait levels. Results A higher order model with a global irritability dimension and Proneness to Anger, Internalized Negative Emotional Reactivity, Externalized Negative Emotional Reactivity and Reactive Aggression sub-dimensions showed good to excellent fit in both parent-report and self-report. The global irritability dimension had a strong influence on all item variance (ω Hierarchical; parent report = .0.94, ω Hierarchical; self report = .90). Proneness to Anger, Externalized Negative Emotional Reactivity and Reactive Aggression decreased with age in males, whereas Internal Negative Emotional Reactivity increased with age in females. Internalized Negative Emotional Reactivity was associated with internalizing traits, over and above global irritability. ODD and ADHD were predicted primarily by the global irritability. Conclusion Although irritability can be estimated as an essentially unidimensional construct, differential associations of Internalized Negative Emotional Reactivity with gender and age, and internalizing psychopathology warrant examination in clinical populations. These results support TIDES-13 as a reliable and valid multidimensional measure of irritability and thus may be useful for research and clinical purposes.