The study examined the factor structure and longitudinal measurement invariance over three time points (1-year apart) of the Strengths and Difficulties Questionnaire-Self Report (SDQ-SR) for ratings provided by adolescents in Greece. It used exploratory structural equation modelling (ESEM) to achieve these two goals. At time point one, a total of 968 adolescents (males = 508, and females = 460) between 12 and 17.9 years completed the SDQ-SR. In relation to factor structure, ESEM tested the fit of one- to five-factor models. The findings were interpreted as indicating most support for the ESEM model with three factors (the factors being dysregulation, peer problems, and prosocial behaviour). This model showed support for configural invariance and full metric invariance across the three time points. Except for two thresholds, all other thresholds were also invariant across the three time points. Thus, there was good support for longitudinal measurement invariance. The implications of the findings for use of the SDQ-SR are discussed.