Auxiliary Verb Constructions in Altai-Sayan Turkic is a comprehensive survey of the rich system of auxiliary verbs found in the Altai-Sayan Turkic languages spoken in south central Siberia. This includes a discussion of the range of patterns of inflection in the auxiliary verb constructions, the development of various verbal affixes that were originally auxiliary verbs, and the wide array of functions that auxiliary verb constructions have in this group of languages. These latter include the usual tense, mood, and aspect categories that are commonly associated with auxiliary verbs across the languages of the world. In addition, auxiliary verb constructions have several less typical functions in the Altai-Sayan Turkic languages. These include both unusual modal or aspectual categories like unexpected action or 'pretend to' forms and categories relating to so-called verbal 'orientation' or 'direction' and 'version'. In the former instance, the forms mark motion toward or away from the subject, topic, or discourse locus, while the latter formations indicate whether a subject or a nonsubject is the participant primarily affected by the action of the verb.