In 1987 the U.S. Census Bureau created a universe of private elementary and secondary schools for the National Center for Education Statistics (NCES). This universe has been updated every 2 years through list frame updating and area frame updating. For the list frame updating, lists of private schools are obtained from various associations around the country. The area frame is updated by creating an independent list of all private schools within a nationally representative sample of counties. This document provides an evaluation of the 1993 list frame and area frame updating operations, which are an update of the 1991 operations. Characteristics of the schools identified in the updating are described, and the impact that the list and area frames have on characteristics of the private school universe is described. It is concluded that the list frame updating operation continues to be effective in improving the coverage of private schools. Overall, the list frame updating added 8% to the universe. Results indicate that the combination of the list frame and area frame produces nearly complete coverage for the Private School Survey. Since area frame updating estimated that about 8% of the universe is missing, continuing this area frame updating is necessary to achieve a more complete private school universe. (Contains 20 tables.) (SLD)