In Indonesia, Bahasa Indonesian (BI) is the designated national and official language. However, deficiencies in Indonesian proficiency are found in a wide range of individuals. A test battery to measure proficiency level was developed, consisting of a writing test, a grammar test, and a cloze test. The writing test was an essay, in which five components were assessed, namely, content, organization, vocabulary, language, and mechanics. The grammar test was a 50-item multiple-choice instrument measuring practical grammatical usage. The cloze test, developed as a possible alternative to the others, had a multiple-choice format. Three brief passages had words deleted at regular intervals. Subjects tested were 103 graduate students and 10 college lecturers. On the writing test, the graduate students' scores ranged from "poor" to "good," while the lecturers' scores were mostly in the "good" range. The test was found to be reliable and valid. Grammar test results showed a wide range of scores, with similar results from graduate students and lecturers. Areas for test improvement were identified. Cloze test scores, while higher than grammar test scores, showed similar patterns. Comparison of the results revealed the lowest correlation between writing and grammar tests, and the highest correlation between grammar and cloze tests. (MSE)