LAUSR

•Argues that explaining national declines in test scores is as important as explaining increases.•Interviews with Australian experts on reasons for Australia’s large decline in PISA scores.•Uses microdata from PISA and TIMSS scores to test expert explanations for decline.•Finds that decline is pervasive across Australian states and social class groups.•Finds that there is no clear explanation for the large decrease in Australia’s PISA scores.