This report summarises Year 6 pupils' attainment in the Progress in International Reading Literacy Study (PIRLS) survey of 2016 in Northern Ireland and explores the context of that attainment. PIRLS is an international comparison study of reading at ages 9-10. PIRLS has a five-yearly cycle. Northern Ireland took part in PIRLS for the second time in 2016, having previously participated in the 2011 cycle. The report compares performance in Northern Ireland with that of the six comparator countries: (1) Canada; (2) England; (3) New Zealand; (4) Poland; (5) Republic of Ireland; and (6) Singapore. These countries were selected because they have some similarities with Northern Ireland and/or because they are high performers and/or because they have demonstrated significant improvement between PIRLS cycles. The report compares Northern Ireland's performance in PIRLS 2016 with the performance in PIRLS 2011. Where possible, the report also explores whether the background factors that impact on attainment have changed between these two cycles of PIRLS. [For the executive summary to this report, "PIRLS 2016 in Northern Ireland: Executive Summary," see ED590518.]