List-assisted random digit dialing (RDD) designs became popular in the late 1980s and early 1990s. Work done by the Bureau of Labor Statistics and the University of Michigan in 1993 resulted in the development of the underlying theory for these designs as well as the evaluation of various alternative sampling plans to optimize the method. Recent research to reevaluate these designs in light of the significant changes in the telephone system over the past decade is presented in this article. The article provides background on the development of list-assisted designs, and recent changes in the U. S. telephone system are reviewed. Using 1999 data from Survey Sampling, Inc., an analysis of the current state of the telephone system is presented, and a reoptimization of the earlier designs is undertaken. Results from the earlier work are compared with findings from the 1999 data.