Speech in children should be viewed as a developing skill. During acquisition the child becomes increasingly capable of organizing linguistic structure at a number of different levels concurrently. One boy seemed to have strategies for simplifying the tasks of speech reception and production. He would incorporate the immediately prior utterance, or some portion of it, intact into his utterance as if to avoid structuring his entire utterance from scratch. Another strategy was to extend his repertoire of structures to express more complex ideas simply by combining two existing structures without reordering any of the elements to match adult syntax. If such strategies are widespread they may account for the recorded facts about the development of children's question forms. Psychological variables, commonly called performance factors, should not be regarded merely as putting restrictions on the extent to which a child's linguistic knowledge can be expressed. Rather, they affect the manner in which syntactic structures develop. Just as the acquisition of linguistic structure is affected by psychological processes, so is the efficiency of these processes affected in its turn by the child's growing linguistic knowledge.