||Young children are precocious language learners and, in service of this, tend to map novel words to unknown referents. Though useful, this tactic increases difficulty for learning novel words that refer to known referents, a phenomenon called the synonym effect. This study investigated how different environmental supports affect this word learning disparity, using the context of shared book reading. Fifty-two 3-year-olds were randomly assigned to four reading conditions that varied in amount of child engagement. Novel target words included synonyms and nonsynonyms. The most effective reading condition for helping children learn new words was also one of the most engaging conditions; it involved asking ostensive questions and giving corrective feedback. Children in this condition performed best on both a comprehension test and a definition test. Also in this more engaging condition, the synonym effect was eliminated in comprehension test results.