Skills training for teachers is of major importance in order to improve the relationship between teachers and students and at the same time has the potential to improve and develop all other educational processes. A psychoeducational training program for primary and secondary school teachers was implemented in schools in Greece with the main goal to improve teachers' self-reported characteristics relating to self-efficacy and work involvement, and teacher-student relationships. Self-report measures were completed by two groups of teachers (intervention and control groups) before and immediately after the implementation of the training program to assess work engagement, core self-evaluations, and relationships with students. ANCOVA analyses showed significant improvement between the two groups in terms of core-self evaluations and student-teacher relationships after the training program. The implications of these findings as potentially protective factors for teachers' performance and prevention of other school-related distressing phenomena, and the limitations of the study are discussed.