The present dissertation extracted 17,291 questions from Aki, Ryo, and Tai and their mother's spontaneously produced speech data available in the CHILDES database (MacWhinney, 2000; Oshima-Takane & MacWhinney, 1998). The children's age ranged from 1;3 to 3;0. Their questions were coded for (1) yes/no questions that include a sentence-final question marker (ka?, no?, kanaa?), (2) wh -questions, (3) wa-ending questions, (4) one-word or -phrase particle questions, (5) one-word or -phrase questions without any overt lexicogrammatical marking, and (6) multi-word utterances without any overt lexicogrammatical question marking. By drawing on usage-based theories of language acquisition driven by frequency, meaning, and discourse, each question was also coded for whether the referent carried given or new discourse information and whether it was present or absent at the time of speaking. Children's questions emerged around their first birthday, and initially reliant on type-5 questions, and each child exhibited individual differences in both the relative emergence of interrogative cues and the pace. During the two-year observation period, the three children and their parents predominantly asked about referents that carried given information and were also present at the time of speaking, thus co-adapting to keep low the cognitive and communicative demands in their questioning behavior. When the much less frequent questions about referents that were new in the discourse and physically absent were posed, the three children (but not their parents) showed a linguistic sensitivity to the referential status of entities in the world and the mind of speakers in that they tended to use wa-ending as the preferred lexicogrammatical marking when asking about new and absent referents. Parental input seemed to explain only subtle patterns in the children's choice of questions, and the input-acquisition link became even less apparent when questions about new and absent referents were closely inspected; I argue that social asymmetries between children and parents shape the function of questions to such a great extent that the relation between parental input and language development is at best indirect in the acquisition of question constructions. This study seeks to bolster understandings of child-language acquisition and illuminate some of its meaning and usage driven mechanisms. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]