This International Symposium was organized in observance of the twenty-fifth anniversary of the School of Dentistry of the University of Alaama in Birmingham. Immunoglobulin A was chosen as the subject of the Symposium because of its broad scope in relation to all biologic sciences, as well as for its particular relevance to prevention of the most common human disease-dental caries. More than 500 scientists, from 13 countries, met in Birmingham, Alabama to review critically past and current research on IgA and to outline goals for integrating future investigations of the many facets of the IgA system.