This book gathers the peer-reviewed papers presented at the 17th International Conference on Alkali-Aggregate Reaction in Concrete (ICAAR), held in Ottawa, Ontario, Canada, on May 19–24, 2024. It highlights the latest advances and innovations in the field of internal swelling reactions, particularly alkali-aggregate reaction (AAR), and combined mechanisms such as delayed ettringite formation (DEF).  The conference topics encompass understanding the reaction mechanisms and the affecting factors; testing methods and preventative measures; diagnosis, evaluation, and prognosis; monitoring and NDT; structural effects and modeling at all scales; repair and remedial measures; and combined mechanisms (e.g., DEF). The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.