Indigenous students, a subgroup of the Australian student population, produce poorer educational outcomes and continue to produce persistently lower attendance rates than non-Indigenous peers. Currently, governments collect and monitor student attendance as an indicator of students' educational achievement and a key performance measure of schools for attributing school funding, and to inform future educational policy and practice. Researching urban Indigenous students' attendance, we sought comparative attendance data from previous research and government collections. Reaching back 30 years, the investigation identified a lack of complete, valid data with verified integrity at all levels of data aggregation, providing researchers with sources of often incomplete, unsuitable, or compromised attendance data. While Australian schools collect students' attendance every school day, the national attendance collection continues to collect and aggregate part-year attendance samples. Improvements in the national attendance collection are urgently needed from which robust analyses and evaluations can accurately inform policy and practice.