The modified version of the Conflict Tactics Scale (M-CTS), originally created by Straus in 1979, is one of the most extensively used instruments to detect violent verbal and physical behaviours in youths' and adolescents' dating relations. The aim of the present work was to analyze the psychometric properties of the instrument and to validate its adequacy in the Spanish population. The sample was made up of 5,355 Spanish youths from the Community of Madrid, ages between 16 and 26 years. By means of confirmatory factor analysis, four factors that were consistent with the theory and with previous research were identified: arguments, psychological/verbal aggression, slight physical aggression, and severe physical aggression. It is concluded that the scale assesses the presence of various types of aggression in youths' and adolescents' dating relationships with sufficient psychometric guarantees.