We hypothesize that the conceptual relation between a verb and its direct object can make a sentence easier (‘the cat is eating some food’) or harder (‘the cat is eating a sock’) to parse and understand. If children's limited performance systems contribute to the ungrammatical brevity of their speech, they should perform better on sentences that require fewer processing resources: children should imitate the constituents of sentences with highly predictable direct objects at a higher rate than those from sentences with less predictable objects. In Experiment 1, 24 two-year-olds performed an elicited imitation task and confirmed that prediction for all three major constituents (subject, verb, direct object). In Experiment 2, 23 two-year-olds performed both an elicited imitation task and a sticker placement task (in which they placed a sticker on the pictured subject of the sentence after hearing and imitating the sentence). Children imitated verbs more often from predictable than unpredictable sentences, but not subjects or objects. Children's inclusion of constituents is affected by the conceptual relations among those constituents as well as by task characteristics.