Understanding early school leaving (ESL) remains a key issue on political and academic agendas. Most research focuses on the experiences of young people who intend to leave or have left school early without a qualification from secondary education. In addition, most studies focus on regular secondary schools. We aim to add to this literature by studying how school staff in regular secondary and adult education schools explain ESL, and to understand how both groups' views differ. We also study whether school climate has an effect on the explanations of ESL given by staff. We analysed survey data collected in Flanders (northern part of Belgium) among 780 staff members using exploratory factor analysis and multilevel modelling. Findings indicate that staff in adult education have moderate views on the causes of ESL compared to staff in regular education. Staff in adult education have a strong focus on student-focused explanations for ESL, rather than on contextual or systemic explanations. Future research could delve deeper into the impact of school characteristics, conduct more cross-comparative research and/or include more views on diversity. Policymakers could prioritise the follow-up of ESL, including feedback mechanisms to inform school staff on reasons why individual students decided to leave school early.