The cross-thematic curriculum (CTC) for school education has recently been implemented so that the quality of the Greek educational system is improved. This study aimed at assessing social and emotional learning competencies and CTC-related skills of 541 Greek students aged 11–13. Data triangulation was also used for validating these findings, having 145 school teachers reporting their perceptions on students' skills. Both students and teachers reported moderate scores of all students' skills. Multivariate analysis revealed that gender remained a significant predictor for high scores of all students' skills, and that the higher the grade level of the students, the lower the mean emotional support, social, and CTC-related skills scores. The mean score of CTC-related skills was very low according to both students and teachers.