This book discusses the first language acquisition of three morphosyntactic mechanisms of transitivity alternation in arctic Quebec Inuktitut. Data derive from naturalistic longitudinal spontaneous speech samples collected over a nine-month period from four Inuit children. Both basic and advanced forms of passive structures are shown to be used productively by Inuktitut-speaking children at an early age relative to English-speaking children, but consistent in age with speakers of non-Indo-European languages reported on in the literature; potential explanations of this difference include frequency of caregiver input and details of language structure. Morphological causatives appear slightly later in the acquisition sequence, and their first instances reflect use of unanalyzed routines. Lexical causatives are present from the earliest ages studied. Evidence of a period of overgeneralization of lexical causatives in one subject at the same time as the morphological causative shows signs of being productively acquired suggests that the seeming overgeneralization may reflect nothing more than as yet unstable use of the morphological causative. Noun incorporation structures are shown to be used productively by Inuktitut-speaking children at an early age relative to Mohawk-speaking children; potential explanations of this difference include details of language structure and relative language use in the environments of the learners. Findings are considered in light of current debates in the literature concerning continuity versus maturation of grammatical structure, and concerning the functional categories available to the child at early stages of acquisition. Data presented argue against late maturation, and suggest that all functional categories may be accessed by the Inuktitut-speaking child early in the acquisition process.