The study presents validation of the Russian version of Effortful Control (EC) scale of the Early Adolescent Temperament Questionnaire-Revised (EATQ-R) in samples of 1764 self-reports and 187 parent reports of 10-17-year-olds. Confirmatory factor analysis supported a common factor and Activation Control and Inhibitory control/Attention latent constructs; the scales demonstrated satisfactory internal consistency and test-retest reliability. Gender and age differences supported the discriminative validity of the Effortful Control scales. Correlations with personality traits measured by the Inventory of Children's Individual Differences-Short version (ICID-S) and with well-being measured by the Strengths and Difiiculties Questionnaire (SDQ) supported criterion validity of the EC scales. Effortful Control and its components were positively related to personality domains of Consciousness and Agreeableness, and to prosocial behaviour, and negatively related to the Neuroticism domain and mental health problems. Correlations with externalising problems were stronger than with internalising problems. In general, the findings were consistent across different informants. Overall, the Russian version of the EATQ-R Effortful Control scale showed reliability and validity comparable to similar measures of Effortful Control widely used in international research.