The U.S. Census Bureau conducts the Schools and Staffing Survey (SASS) for the National Center for Education Statistics (NCES). The SASS is a set of integrated self-administered surveys designed to obtain national information on all aspects of the school system. The Teacher Listing Form (TLF) is the first in the SASS series. It is sent to the principal early in the school year to list all teachers at the school. These results are used to select teachers from the school to participate in the SASS. In 1994, the Teacher List Validity Study uncovered some problems with the TLF. This document reports on cognitive research conducted to find out why respondents made the mistakes they did so that the TLF could be improved. A cognitive interview was held with one person from each of 19 sampled schools in Pennsylvania, Maryland, and Virginia (usually the principal). A combination of cognitive techniques, including think-aloud protocols, provided data. The interviews revealed that the TLF needed to be reorganized so that important conceptual information was not interrupted by unrelated information. Some instructions needed to be rearranged for clarity. Better definitions of what to include or exclude were required. Respondents had difficulty in reporting the subjects teachers were qualified to teach, so a decision rule was designed to help them choose a subject. Breaking the data into sections that correspond more closely to the real-world organization of schools is also recommended. An appendix contains the TLF. (Contains two tables.) (SLD)