This study examined the special educational needs (SEN) allocation practices across Austrian federal states by (a) surveying the current allocation practices, (b) exploring the reasons for disparities among the states, and (c) conducting a process analysis from all stakeholders' perspectives. The research comprised four sub-studies: data analysis on 26,102 compulsory school pupils with SEN to analyze socio-demographic, disability forms, and educational pathways differences; a survey (N = 289) among teachers, parents, and school officials on the SEN assessment processes; an analysis of assessments and decisions (N = 454; 13,705 pages) to identify quality characteristics in SEN allocation; and expert interviews (N = 31) to provide a comprehensive view of the allocation process.