Standardised tests of academic basic skills are an established feature of contemporary Australian schooling. Assessment results are widely reported and directly influence educational policymaking. Furthermore, Australian national educational priorities are linked to educational system accountability via the results of standardised tests. Given the influence and importance of assessment data, this paper aimed to collate publicly available data from four assessment programmes undertaken by Australian students, and document long-term trends in average achievement across all available assessments. Results are reported from three international assessments, the Progress in International Reading Literacy Study, the Trends in International Mathematics and Science Study and the Programme for International Student Assessment (PISA), along with the only Australian assessment, the National Assessment Program: Literacy and Numeracy. Of these four, only PISA demonstrated systematic declines in average scores over time. For the remaining three programmes, results in the primary school years showed initial improvements that were subsequently maintained over remaining iterations of the tests. In secondary school, students' average results neither declined nor increased appreciably over time. The consensus of the four largest assessment programmes undertaken by Australian students since 1995 thus fails to support the prevailing narrative of a broadscale decline in academic skills attainment.