A historical-comparative study of the sonorant system of Athabaskan, Eyak, and Tlingit, American Indian languages of Alaska, is presented. In this study, sonorants are considered as a class rather than as a constituent of the general consonant group. An opening section looks at the development of the generally recognized Proto-Athabaskan (PA) sonorants, and subsequent sections consider, in greater detail, specific PA sonorants, stem-initial sonorants, ablaut and nasalization in Athabaskan, stems with an internal sonorant or fricative, and Na-Dene sonorant systems (PA, Eyak, PA-Eyak correspondences, Tlingit, Tlingit/Eyak/Athabaskan correspondences, Na-Dene/Haida/Tsimshian). Appended sections explain transcriptions and abbreviations, and an index of the PA stems. Contains 143 references. (MSE)