This book is a revised version of my Ph.D. dissertation that was submitted to the Massachusetts Institute of Technology in 1983. Although much of the analysis and argumentation of the dissertation has survived rewriting, the organization has been considerably changed. To Paul Kiparsky and Morris Halle, lowe a major debt. Not only has it been a great privilege to work on phonology with both of them, but it is hard to imagine what this piece of research would have looked like without them. (They, of course, may well imagine a number of appropriate ways in which the work could be different had I not been involved .... ) In addition, special thanks are due to Ken Hale, the third member of my thesis committee. Our discussions of a variety of topics (including tone) helped me to keep a broader outlook on language than might have otherwise been the result of concentrating on a thesis topic.