To promote and encourage the use of SCC, ACI Committee 236, Material Science of Concrete, and ACI Committee 237, Self-Consolidating Concrete, organized two technical sessions on "Workability of SCC: Roles of Its Constituents and Measurement Techniques" at the ACI Spring 2005 Convention in New York City, New York. Eleven papers were presented covering a wide range of practical case studies and research projects on the design, testing, placement, and performance of SCC. This Special Publication (SP) contains 10 of the papers presented at the sessions. Six of the papers deal with the mixture proportions and the effects of raw materials on workability; two of them deal with the rheometer testing of SCC; one deals with form pressure; and one deals with the structural response of SCC frames under earthquake loading.