Positive and negative what, why and yes/no questions with the 3sg auxiliaries can and does were elicited from 50 children aged 3;3–4;3. In support of the constructivist “schema-combination” account, only children who produced a particular positive question type correctly (e.g., What does she want?) produced a characteristic “auxiliary-doubling” error (e.g., *What does she doesn't want?) for the corresponding negative question type. This suggests that these errors are formed by superimposing a positive question frame (e.g., What does THING PROCESS?) and an inappropriate negative frame (e.g., She doesn't PROCESS) learned from declarative utterances. In addition, a significant correlation between input frequency and correct production was observed for 11 of the 12 lexical frames (e.g., What does THING PROCESS?), although some negative question types showed higher rates of error than one might expect based on input frequency alone. Implications for constructivist and generativist theories of question-acquisition are discussed.