I. L. TYLER AND FRED HUBBARD PREPARED CHAPters on “Uniformity, Segregation and Bleeding” and “Workability and Plasticity,” in ASTM STP 169 [1,2]. C. A. Vollick combined, revised, and updated these two chapters into “Uniformity and Workability” for ASTM STP 169A [3]. D. T. Smith revised and updated this chapter in ASTM STP 169B [4]. John M. Scan-Ion revised, updated, and changed the title to “Factors Influencing Concrete Workability” in ASTM STP 169C [5]. The current edition reviews, revises, and updates the topics as addressed by the previous authors. Mr. Tyler was with the Portland Cement Association, Mr. Hubbard with the National Slag Association, Mr. Vollick with Sika Chemical Corporation, Mr. Smith with Marquette Cement Manufacturing, and Mr. Scanlon was a senior consultant with Wiss, Janney, Elstner Associates, Inc.