The transition from primary to secondary school is a highly stressful period for vocational school students because they need to adjust both to the school and their future vocation at the same time. The current study examines the relationship between the school climate, teacher support, school engagement and subsequent students' school adjustment by testing a two-wave moderated mediation model. The study included 251 vocational secondary school first-year students from Serbia. A significant indirect effect of the perceived school climate on school adjustment through school engagement was determined. Teacher support had a moderating role on the relationship between school climate and school engagement. Students from Serbia reported lower school engagement and teacher support than their peers from other countries. The findings indicate that school engagement is a mechanism of adjusting to a new school environment and that teachers have a role as catalysts of that adjustment.