Sponsored by ACI Committee 236. This volume consists of ten papers that were presented at a technical session, sponsored by ACI Committee 236, Materials of Science of Concrete, at the ACI Fall 2006 Convention in Denver, CO. Papers include "Nanotechnology in Construction: A Roadmap for Development", " Nanotechnology and Concrete: Research Opportunities", "Molecular Engineering of the Cohesion in Neat and Hybrid Cement Hydrates", and "Use of Atomic Force Microscopy and Nanoindentation for Characterization of Cementitious Materials at the Nanoscale".