Preface The papers presented in this volume were included in a three-part session sponsored by ACI Committee 201@ Durability of Concrete@ about sulfate attack on concrete at the ACI Convention in Philadelphia@ PA@ on October 23-24@ 2016. In line with the practice and requirements of the American Concrete Institute@ peer review@ followed by appropriate response and revision by authors@ has been used. Deterioration of concrete due to sulfate attack is a complex process characterized by multiple damage manifestations including volumetric expansion@ cracking@ spalling@ softening@ and in some cases mushiness. Sulfate attack can generally be classified as internal or external to the cementitious matrix@ and the underlying damage modes can be chemical or physical. The scope of papers involves a multitude of theoretical and experimental aspects of different forms of sulfate attack. Readers are urged to critically evaluate the work presented herein@ in the light of the large body of knowledge and scientific literature on this durability topic. We dedicate this volume of papers to the memory of Prof. Robert L. Day@ past chairman of Canadian Standards Association (CSA) Committee A23.1/A23.2 (Concrete Materials and Construction)@ for his invaluable contributions to the field of durability of concrete. The editors sincerely thank all the presenters in this session and authors of the articles included in this SP@ as well as the reviewers for their objective assessment of the papers. Their technical contributions provided a holistic perspective of sulfate attack on concrete.