This paper discusses the construct of trait emotional intelligence (trait EI or trait emotional self-efficacy) with emphasis on measurement in children. The Trait Emotional Intelligence Questionnaire-Child Form (TEIQ-ue- CF) is introduced and its development and theoretical background are briefly explained. It is shown in two independent studies that the TEI-Que-CF has satisfactory levels of internal consistency ( = 0.76 and = 0.73, respectively) and temporal stability [r = 0.79 and r(corrected) = 1.00]. Trait EI scores were generally unrelated to proxies of cognitive ability, as hypothesized in trait EI theory (Petrides et al. in Matthews et al. (eds) Emotional intelligence: knowns and unknowns-series in affective science. Oxford University Press, Oxford, pp 151-166). They also differentiated between pupils with unauthorized absences or exclusions from school and controls. Trait EI correlated positively with teacher-rated positive behavior and negatively with negative behavior (emotional symptoms, conduct problems, peer problems, and hyperactivity).