The present paper investigates teachers' guidance from the transformational leader of the school unit in the implementation of cross-thematic teaching. More Specifically, the research focuses on (a) the existence of transformational practices and behaviors of school principals and (b) the thematic of the formal discussions of the Teachers' Association on cross-curricular teaching and the achievement of the School's objectives through a cross-curricular approach. It is concluded that there is a positive relationship between the practices, behaviors of the transformational leader of the school unit, and the explanation of the intersectional teachings and the expected results (R = 0.550, R square = 0.303, F = 30.401, p <0.00). The results can be taken into account in future training activities for teachers and principals.