This study provides information about the total and component scores of the Test of English as a Foreign Language (TOEFL). First, the study provides comparative global and component estimates of test-retest, alternate-form, and internal-consistency reliability, controlling for sources of measurement error inherent in the examinees and the testing administration context. The study also provides information about differential changes in subtest difficulty on repeated application over a small interval of time (8 days). This study considered the phenomenon of "item bounce" and reflected the comparative stabilities of difficulty estimates within item type over repeated test administrations. Although test-length-adjusted reliability estimates were found to be adequately high across reported component and total test scores, the study contained several inherent limitations, chief of which was the comparatively small sample of 329 subjects. Attrition and design features reduced the test-retest reliability estimates to separate repeating subgroups of 101 and 91 persons, and alternate-form reliability estimates were based on 52 and 25 persons. In addition, samples were not perfectly representative of the current TOEFL population. (Contains 10 tables and 14 references.) (SLD)