In 2016, 50 countries and 11 benchmarking participants (regional entities) took part in PIRLS, while 14 countries and two benchmarking participants also took part in the ePIRLS assessment of online reading.
In 2021, 60 countries and 7 benchmarking participants plan to participate in PIRLS. It is expected that roughly half the participants will administer PIRLS on paper, and roughly half on computer (with ePIRLS integrated into the digital PIRLS assessment). Countries intending to participate are listed below.
Countries Participating in PIRLS
| Albania | France | North Macedonia |
| Australia | Georgia | Northern Ireland |
| Austria | Germany | Norway |
| Azerbaijan | Hong Kong SAR | Oman |
| Bahrain | Hungary | Poland |
| Belgium (Fl) | Iran | Portugal |
| Belgium (Fr) | Ireland | Qatar |
| Bosnia and Herzegovina | Israel | Russian Federation |
| Brazil | Italy | Saudi Arabia |
| Bulgaria | Kazakhstan | Serbia |
| Canada | Kosovo | Singapore |
| Chile | Kuwait | Slovak Republic |
| Chinese Taipei | Latvia | Slovenia |
| Croatia | Lithuania | South Africa |
| Cyprus | Macao SAR | Spain |
| Czech Republic | Malta | Sweden |
| Denmark | Montenegro | Turkey |
| Egypt | Morocco | United Arab Emirates |
| England | Netherlands | United States |
| Finland | New Zealand | Uzbekistan |
Benchmark participants
Ontario, Canada
Quebec, Canada
Denmark (Grade 3)
Moscow City, Russia
South Africa (5th Grade)
Abu Dhabi, UAE
Dubai, UAE