This first English edition of Trubetzkoy's classic work, translated by Christiane A.M. Baltaxe, treats some 200 phonological systems attested in the world's languages. Central to the book is the author's "Theory of Distinctiveness" which states that there are certain minimal distinctive phonic properties that appear to be universal characteristics of all language systems. Following forewords by the translator and the Prague Linguistic Circle is the author's introduction to phonology and phonetics, and phonology and phonostylistics. Contents of the first part of this work, "The Theory of Distinctiveness; The Distinctive or Meaning-differentiating Function of Sound" are the following chapters: (1) Basic Notions; (2) Rules for the Determination of Phonemes; (3) Logical Classification of Distinctive Oppositions; (4) Phonological Classes of Distinctive Oppositions; (5) Types of Neutralization of Distinctive Oppositions; (6) Phoneme Combinations; and (7) Phonological Statistics. Chapters in Part II, "The Theory of Delimitative Elements; The Delimitative Function of Sound" are (1) Preliminary Remarks; (2) Phonemic and Nonphonemic Boundary Signals; (3) Individual Signals and Group Signals; (4) Positive and Negative Boundary Signals; and (5) The Use of Boundary Signals. Appended are further notes, an author's bibliography, and indexes. (AMM)