The reading literacy skills of Australian adolescents, as measured in successive PISA waves, have declined since 2000. Literacy achievement is not low by international standards, but it is lower in Australia than it is in Anglophone countries with which we compare ourselves, e.g. Canada. Using PISA 2018 and PIRLS 2021 data, we investigated both individual and school-level factors that influence adolescent reading literacy achievement, finding that student-level factors accounted for 80% of variance with only 20% related to schools. Of the school effects, we find a substantial proportion of that variance is related to student peer influences. Among the individual influences, low SES, male, and language background other than English (LBOTE) status are associated with lower levels of achievement. We find that SES operates at both the individual and the school-level to explain variation in achievement. School average SES has a much stronger influence than does individual SES. It is worth noting that differences in student-perceived (PISA) and self-reported (PIRLS) teacher practices were not identified as factors associated with reading achievement gaps. We explore policy implications of our findings, including school funding arrangements. While the main individual-level factors that influence achievement are not directly amenable to policy interventions, they do suggest categories of students for whom additional support would likely generate improvements and help close the reading achievement gap.