The purpose of the study is to evaluate whether the C-test is useful as a test measuring non-native speakers' ability of written language to help teachers and decision-makers select and place limited English proficient students for English as a Second Language (ESL) instruction in high schools in Iowa. The overall usefulness of the C-test is evaluated by examining individual qualities of test usefulness, or six qualities, in current testing theories: reliability, construct validity, authenticity, interactiveness, impact, and practicality. Chapter 1 of this study reports the background: a need for a test measuring non-native speakers' ability of written language to improve assessment procedures for selection and placement for high school ESL instruction; and the history, definition, and evaluation of the C-test.;Chapter 2 explains the process of test development which includes: defining the purpose of the test; defining six qualities of test usefulness; evaluating the C-test usefulness in other studies; describing target language use tasks relevant to the C-test; describing test takers; defining the construct to be measured; describing C-test task; and, finally, examining the C-test usefulness from the perspective of logical analysis. Chapter 3 reports the methods used for data collection and analysis for the pilot and main tests as a basis for the empirical evaluation of test usefulness. Then, Chapter 4 discusses the results examining reliability, construct validity, impact, and practicality from the perspective of the empirical analysis. Finally, Chapter 5 summarizes evaluation of test usefulness qualities, draws conclusions about the overall usefulness of the C-test for this particular setting, and suggests areas for improvement for the future use of the C-test.;In summary, even though authenticity and interactiveness were considered relatively medium, the C-test was highly reliable and practical and provided evidence for construct validity and positive impact. The conclusions, therefore, suggest that the C-test is considered useful as a test measuring written language ability of nonnative speakers for ESL selection and placement in high schools for now. For the future test use, it is recommended that further research with a larger population be conducted to suggest guidelines or scales for appropriate selection and placement.