TIMSS 2015 was the sixth cycle of the IEA Trends in International Mathematics and Science Study (TIMSS). The study was initiated in February 2013 at the first national research coordinators meeting. Framework and instrument development work was carried out in 2013. The field test was conducted in March–April 2014. The data collection for the main survey was carried out in August 2015. The international reports were released in December 2016, followed by the international database and user guide in February 2017.

The following education systems participated in this round of TIMSS:

Argentina (Buenos Aires) Hong Kong SAR Norway
Armenia Hungary Oman
Australia Indonesia Palestine
Bahrain Iran Poland
Belgium (Flemish) Ireland Portugal
Botswana Israel Qatar
Bulgaria Italy Russian Federation
Canada (with Ontario and Quebec as benchmarking systems) Japan Saudi Arabia
Chile Jordan Serbia
Chinese Taipei Kazakhstan Singapore
Croatia Korea Slovak Republic
Cyprus, Kuwait Slovenia
Czech Republic Lebanon South Africa
Denmark Lithuania Spain
Egypt Malaysia Sweden
England Malta Thailand
Finland Morocco Turkey
France Netherlands United Arab Emirates (with Abu Dhabi and Dubai as benchmarking systems)
Georgia New Zealand United States (with Florida as a benchmarking system)
Germany Northern Ireland