23 ICMI Studies have been completed and published up till now. One more Study (ICMI Study 24) is in the process.

In April 2018 the first ICMI Study was published which is available open access (ICMI Study 23)

1. The Influence of Computers and Informatics on Mathematics and its Teaching.
   Co-chairs of the International Programme Committee:  Geoffrey Howson (UK) and Jean-Pierre Kahane (France). Study Conference held in Strasbourg, France, March 1985.
    
2. School Mathematics in the 1990s.
   No general Study Conference. (Study Volume prepared by the editors following a closed international seminar held in Kuwait in February 1986.)
    
3. Mathematics as a Service Subject.
   Co-chairs of the International Programme Committee:  Geoffrey Howson (UK) and Jean-Pierre Kahane (France). Study Conference held in Udine, Italy, April 1987.
    
4. Mathematics and Cognition.
   No general Study Conference. (Study Volume prepared under the responsibility of PME.)
    
5. The Popularization of Mathematics.
   Co-chairs of the International Programme Committee:  Geoffrey Howson (UK) and Jean-Pierre Kahane (France). Study Conference held in Leeds, UK, September 1989.
    
6. Assessment in Mathematics Education.
   Chair of the International Programme Committee:  Mogens Niss (Denmark). Study Conference held in Calonge, Spain, April 1991.
    
7. Gender and Mathematics Education.
   Chair of the International Programme Committee:  Gila Hanna (Canada). Study Conference held in Höör, Sweden, October 1993.
    
8. What is Research in Mathematics Education and What are its Results?
   Co-chairs of the International Programme Committee:  Jeremy Kilpatrick (USA) and Anna Sierpinska (Canada). Study Conference held in College Park, USA, May 1994.
    
9. Perspectives on the Teaching of Geometry for the 21st Century.
   Chair of the International Programme Committee:  Vinicio Villani (Italy). Study Conference held in Catania, Italy, September 1995.
    
10. The Role of the History of Mathematics in the Teaching and Learning of Mathematics.
    Co-chairs of the International Programme Committee: John Fauvel (UK) and Jan van Maanen (Netherlands). Study Conference held in Luminy, France, April 1998.
     
11. The Teaching and Learning of Mathematics at University Level.
    Chair of the International Programme Committee:  Derek Holton (New Zealand). Study Conference held in Singapore, December 1998.
     
12. The Future of the Teaching and Learning of Algebra.
    Chair of the International Programme Committee: Kaye Stacey (Australia). Study Conference held in Melbourne, Australia, December 2001.
     
13. Mathematics Education in Different Cultural Traditions: A Comparative Study of East Asia and the West.
    Co-chairs of the International Programme Committee: Klaus-D. Graf (Germany) and Frederick K.S. Leung (Hong Kong). Study Conference held in Hong Kong, SAR China, October 2002.
     
14. Applications and Modelling in Mathematics Education.
    Chair of the International Programme Committee: Werner Blum (Germany). Study Conference held in Dortmund, Germany, February 2004.
     
15. The Professional Education and Development of Teachers of Mathematics.
    Co-chairs of the International Programme Committee: Ruhama Even (Israel) and Deborah Loewenberg Ball (USA). Study Conference held in Aguas de Lindóia, Brazil, May 2005.
    Documents: Study Volume: NISS Series number 11.
    Discussion document: Click here.
    Proceedings of ICMI Study Conference: click here.
     
16. Challenging Mathematics in and Beyond the Classroom.
    Co-chairs of the International Programme Committee: Edward J. Barbeau (Canada) and Peter J. Taylor (Australia). Study Conference held in Trondheim, Norway, June 2006.
    Documents: Study Volume: NISS Series number 12.
    Discussion document: click here.
    Proceedings of ICMI Study Conference: click here.
     
17. Digital Technologies and Mathematics Teaching and Learning: Rethinking the Terrain.
    Co-chairs of the International Programme Committee: Celia Hoyles (UK) and Jean-Baptiste Lagrange (France). Study Conference held in Hanoi, Vietnam, December 2006.
    Documents: Study Volume: NISS Series number 13.
    Discussion document: click here.
    Proceedings of ICMI Study Conference: click here.
     
18. Statistics Education in School Mathematics: Challenges for Teaching and Teacher Education.
    Study organised jointly by ICMI and the International Association for Statistical Education (IASE).
    Chair of the International Programme Committee: Carmen Batanero (Spain). Study Conference held in Monterrey, México, July 2008. 
    Documents: Study Volume: NISS Series number 14.
    Discussion Document: click here.
    Proceedings of ICMI Study Conference: click here.
    Executive Summary: click here.
     
19. Proof and Proving in Mathematics Education
    The two co-chairs are Gila Hanna, University of Toronto, Canada, and Michael de Villiers, University of KwaZulu-Natal, South Africa. Study Conference held on May 10-15, 2009 in Taipei, Taiwan. 
    Documents: Study Volume: NISS Series number 15.
    Discussion Document: click here.
    Proceedings of ICMI Study Conference: click here.
     

20. Educational Interfaces between Mathematics and Industry (EIMI)
    This Study is a joint project with the International Council for Industrial and Applied Mathematics (ICIAM). The co-chairs of this 20th ICMI Study are Alain Damlamian (Université Paris XII, France) and Rudolf Sträßer (Justus-Liebig-Universitaet Giessen, Germany).  José Francisco Rodrigues (Universidade de Lisboa, Portugal) was the organiser of the Study Conference which was held on October 11-15, 2010 in Lisbon, Portugal.
    Documents: Study Volume NISS Series Number 16
    For Discussion Document click here: Study website
    Proceedings of ICMI Study Conference (to be added)
     

21. Mathematics Education and Language Diversity The 21st ICMI Study was published in 2016. The editors are Barwell, R., Clarkson, P., Halai, A., Kazima, M., Moschkovich, J., Planas, N., Phakeng, M., Valero, P., Villavicencio, M. . The book provides a broad critical survey of research on mathematics education and language diversity: http://www.springer.com/de/book/9783319145105 The study conference took place in Águas de Lindóia, São Paulo, Brasil, September 16-20, 2011. More information can be found on the website: www.study-21-conf.fe.usp.br/index.php/home
    Documents:Study Volume:
    Discussion Document: (to be added)
    Proceedings of ICMI Study Conference: (to be added)
     

22. Task Design The Study Chairs of ICMI Study 22 on Task Design were Anne Watson and Minoru Ohtani. The Study Conference was held July 22nd to July 26th 2013 at the Department of Education, University of Oxford, UK.
    Proceedings of the international Conference: available online: http://hal.archives-ouvertes.fr/hal-00834054
    Plenary talks and plenary panel presentations of the Study Conference of ICMI Study 22 can be found here.
    The volume has been be published in the fall of 2015: http://www.springer.com/de/book/9783319096285
    The volume has been be published in the fall of 2015: http://www.springer.com/de/book/9783319096285
    Discussion Document: (to be added)
     

23. ICMI Study 23: Primary Mathematics Study on Whole Numbers

    Professor Mariolina Bartolini of University of Modena-Reggio Emilia, Italy and Assistant Professor Sun Xuhua of the University of Macau, China were the Co-Chairs of this study. The book was published OPEN ACCESS in April 2018 with the title "Building the foundation: whole numbers in the primary grades."The IPC meeting has been held January 19-24,2014 at the IMU Secretariat in Berlin, Germany.
    The Discussion document can be found here and on the ICMI Study 23 website:http://www.umac.mo/fed/ICMI23/paper.html The CONTEXT FORM can be found here. The Study Conference was held at the University of Macau, Macau SAR, China, from June 3 to 7, 2015. Information about the conference can be found on the study conference website and the Discussion Document.
    The book is available for free download here: https://link.springer.com/book/10.1007%2F978-3-319-63555-2