Onondaga is an Iroquoian language spoken at the Six Nations Reserve, near Brantford, Ontario, and at Onondaga Nation, near Syracuse, New York. Once spoken by a large Iroquoian population in New York State, Onondaga is now spoken by only a small number of individuals. This comprehensive dictionary – the first of its kind – provides an invaluable tool for the teaching and preservation of the Onondaga language. The Onondaga-English/English-Onondaga Dictionary is the result of Hanni Woodbury's thirty years of research conducted with contemporary speakers and her study of nineteenth- and twentieth-century textual sources. The dictionary provides meanings and inflections for each lexical base, as well as cross-references for related bases and additional grammatical, phonological, historical, and cultural information. The appendices, organized under the headings 'Nature,' 'People,' and 'Household and Community,' include lists of words that play an important role in daily life. This much-needed resource will be invaluable to ongoing efforts to sustain this endangered language.