The symposium on Living with Marginal Aggregates was held at the Seventy-eighth Annual Meeting of the American Society for Testing and Materials held in Montreal, Canada, 22—27 June 1975. The symposium was sponsored by Committee C09 on Concrete and Concrete Aggregates, R. E. Philleo, chairman, and organized by Subcommittee C09.01.02 on Papers and Symposia, C. J. Andres, C. H. Best, and L. M. M. Dolar-Mantuani. C. H. Best, Kansas State University, presided as symposium chairman.