1938. A Word Index to Wolfram's Parzival. [With Alfred Senn.] Madison: University of Wisconsin, Department of German. 248 pp.
1940-1949
1940. A Word Index to the Poems of Walther von der Vogelweide. [With R-M. S. Heffner.] Madison: University of Wisconsin, Department of German. 78 pp. [Reprinted by University of Wisconsin Press, 1950.]
1950-1959
1951. A Grammar of Formal Written Japanese. [With Lloyd Faust.] (Harvard-Yenching Institute Studies, 5.) Cambridge: Harvard University Press. x, 153 pp.
1952. Proto-Indo-European Phonology. Austin: University of Texas Press and Linguistic Society of America. xi, 129 pp. [Reprinted numerous times.] Online version edited by Jonathan Slocum, 2005.
1953. The Alliteration of Old Saxon Poetry. Norsk Tidsskrift for Sprogvidenskap, suppl. vol. 3. Oslo: H. Aschehoug. 231 pp.
1954. The Alliterations of the Edda. [With J. L. Dillard.] Austin: The University of Texas, Department of Germanic Languages. 168 pp.
1956. The Development of Germanic Verse Form. Austin: University of Texas Press and Linguistic Society of America. xix, 217 pp. [Reprinted in 1971 by Gordian Press, New York.]
1958. Active German: An Elementary Grammar. [With Helmut Rehder and George Schulz-Behrend.] New York: Dryden Press. xxi, 238 pp.
1958. The Alliterations of the Beowulf. [With Takemitsu Tabusa.] Austin: The University of Texas, Department of Germanic Languages. 134 pp.
1959. Review and Progress in German. [With Helmut Rehder, Leroy Shaw, and Stanley N. Werbow.] New York: Holt, Rinehart & Winston. xiv, 265 pp.
1960-1969
1960. The Alliterations of the Christ, Guthlac, Elene, Juliana, Fates of the Apostles, Dream of the Rood. [With Virginia F. Dailey.] Austin: The University of Texas, Department of Germanic Languages. 401 pp.
1961. A Word Index to Wolfram's Parzival, 2nd ed. Pp. 1-178 in Collected Indexes to the Works of Wolfram von Eschenbach, ed. by R-M. S. Heffner. Madison: University of Wisconsin Press.
1962. Active German: An Elementary Grammar, revised ed. New York: Holt, Rinehart & Winston. xvi, 228, xliv pp.
1962. Historical Linguistics: An Introduction. New York: Holt, Rinehart & Winston. xiii, 297 pp.
1964. Spectrum: Modern German Thought in Science, Literature, Philosophy, and Art. [Compiled and edited with Helmut Rehder and Hans Beyer.] New York: Holt, Rinehart & Winston. xi, 622 pp.
1965. Selected Vowel Measurements of American English Speech. [With Helen-Jo J. Hewitt.] Austin: University of Texas. 175 pp. [Report produced with some support from the University Research Institute.]
1967. Rekishi gengo gaku josetsu. Japanese edition of Historical Linguistics: An Introduction. Tokyo: Kenkyusha. 295 pp.
1967. A Reader in Nineteenth Century Historical Indo-European Linguistics. [Editor.] Bloomington: Indiana University Press. 266 pp. Online version edited by Jonathan Slocum, 2006.
1968. Directions for Historical Linguistics: A Symposium. [Editor, with Yakov Malkiel.] Austin: University of Texas Press. ix, 199 pp. Online version edited by Jonathan Slocum, 2006.
1969. Einführung in die historische Linguistik. German edition of Historical Linguistics: An Introduction. Heidelberg: Carl Winter. 230 pp.
1969. Introduccion a la linguistica historica. Spanish edition of Historical Linguistics: An Introduction. Madrid: Editorial Gredos. 354 pp.
1970-1979
1972. Descriptive Linguistics: An Introduction. New York: Random House. x, 291 pp.
1972. German: Language and Culture. [With Thomas J. O'Hare and Christoph Cobet.] New York: Holt, Rinehart & Winston. xii, 202 pp. [Accompanied by student's exercise manual and teacher's manual.]
1973. Historical Linguistics: An Introduction, 2nd ed. New York: Holt, Rinehart & Winston. ix, 273 pp.
1974. Proto-Indo-European Syntax. Austin: University of Texas Press. x, 278 pp. [Reprinted in 1980.] Online version edited by Jonathan Slocum, 2005.
1975. An Introduction to Old Irish. [With R. P. M. Lehmann.] New York: Modern Language Association. xv, 201 pp.
1975. Language and Linguistics in the People's Republic of China. [Editor.] Austin: University of Texas Press. ix, 168 pp.
1976. Descriptive Linguistics: An Introduction, 2nd ed. New York: Random House. xi, 339 pp.
1976. Instructor's Manual for Descriptive Linguistics, 2nd ed. New York: Random House. 87 pp.
1976. Workbook for Descriptive Linguistics, 2nd ed. [With Solveig M. V. Pflueger.] New York: Random House. 188 pp.
1977. Nuove tendenze della linguistica storica. Italian edition of Directions for Historical Linguistics: A Symposium. Bologna: il Mulino. 208 pp.
1978. Syntactic Typology: Studies in the Phenomenology of Language. [Editor.] Austin: University of Texas Press. 463 pp. Online version edited by Jonathan Slocum, 2006.
1980-1989
1981. Linguistische Theorien der Moderne. (Germanistische Lehrbuchsammlung, Abteilung A. Sprache, 19A.) Bern: Peter Lang. 173 pp.
1982. Language: An Introduction. New York: Random House. 241 pp.
1982. Perspectives on Historical Linguistics. [Editor with Yakov Malkiel.] (Studies in the Theory and History of Linguistic Science, IV. Current Issues in Linguistic Theory, 24.) Amsterdam: Benjamins. xii, 379 pp.
1984. Workbook for Historical Linguistics, 2nd ed. Dallas: Summer Institute of Linguistics. vii, 92 pp.
1985. Natural Language Processing. [Editor.] Special issue of Computers and the Humanities, Vol. 19, No. 2 (April-June).
1986. Language Typology 1985: Papers from the Linguistic Typology Symposium, Moscow, 9-13 December 1985. [Editor.] (Current Issues in Linguistic Theory, 47.) Amsterdam: John Benjamins. viii, 200 pp.
1986. A Gothic Etymological Dictionary. Based on the third edition of Vergleichendes Wörterbuch der gotischen Sprache by Sigmund Feist. With bibliography prepared under the direction of Helen-Jo J. Hewitt. Leiden: Brill. xx, 712 pp.
1986-87. Computers and Translation. [Editor] vols. 1-2.
1990-1999
1990. Language Typology, 1987: Systematic Balance in Language. [Editor] Amsterdam: Benjamins. 212 pp.
1991. Language Typology 1988: Typological Models in Reconstruction. [Editor, with Helen-Jo Jakusz Hewitt.] Amsterdam: Benjamins. 182 pp.
1992. Historical Linguistics: an Introduction, 3rd ed. London: Routledge. xviii, 288 pp.
1992. Workbook for Historical Linguistics, 3rd ed. Dallas: Summer Institute of Linguistics. viii, 167 pp.
1992. Die gegenwärtige Richtung der indogermanistischen Forschung. (Archaeolingua: Series Minor 2.) Budapest: Archaeological Institute of the Academy of Sciences. 89 pp.
1993. Theoretical Bases of Indo-European Linguistics. London: Routledge. xii, 324 pp.
1995. Residues of Pre-Indo-European Active Structure and their Implications for the Relationships among the Dialects. Innsbrucker Beiträge zur Sprachwissenschaft, Vorträge und Kleinere Schriften 61. Innsbruck: Institut für Sprachwissenschaft der Universität Innsbruck. 74 pp.
1996. Theoretical Bases of Indo-European Linguistics, paperback ed. London: Routledge. vii, 324 pp.
1998. Manuale di linguistica storica. Italian edition of Historical Linguistics: An Introduction. Bologna: Società editrice il Mulino. 380 pp.
1999. Biblical Hebrew: An Analytical Introduction. [With Esther Raizen and Helen-Jo Jakusz Hewitt.] San Antonio, Texas: Wings Press. xv, 387 pp.
2000-2002
2002. Pre-Indo-European. Journal of Indo-European Studies Monograph No. 41. Washington DC: Institute for the Study of Man. xvi, 287 pp.
