Aim. The aim of the study was to analyze how emotional intelligence and temperamental traits - emotional reactivity and activity - are related to the assertiveness. Method. The study used the Social Competence Questionnaire (SCQ), Formal Characteristics of Behavior - Temperament Questionnaire (FCB-TQ(R)) and the Popular Emotional Intelligence Questionnaire (PEIQ). Data was collected from a sample of 204 people including 115 males and 89 females. Results. Results showed that assertiveness is correlated with activity, emotional reactivity, understanding emotions, acceptance of emotions and emotional control. Regression analysis showed that emotional acceptance, emotional reactivity and activity explain 36% of assertiveness in the studied sample.