Little is known about the impact of teachers' questions on child bilingual's heritage language reading process and outcomes. This study examined the role of adults' questions in English-Mandarin bilingual preschoolers' Mandarin word learning, story comprehension, and reading engagement. Ninety-nine 4- to 5-year-old preschoolers in Singapore were assigned to one of the three reading conditions: (a) reading with contextualized questions (e.g., labelling), (b) reading with decontextualized questions (e.g., inference), and (c) reading without questions. The experimenters read three storybooks to the children three times over 2 weeks. Children's general Mandarin proficiency was tested before the intervention, and their target words knowledge and story comprehension were tested before and after the intervention. Children's reading engagement in each reading was assessed with a modified Child Behavior Rating Scale. The results demonstrate that not all aspects of Mandarin performance and reading engagement have benefitted from the experimenter's questions. Contextualized questions were found to significantly enhance children's word meaning explanation and story retelling. Contextualized and decontextualized questions lead to higher increase in social-cognitive engagement but resulted in faster decrease in behavioral and affective engagement over repetitive readings. Furthermore, children's initial Mandarin proficiency influences their reading process and outcomes. Generally, the better their Mandarin vocabulary knowledge was, the more they could enjoy and benefit from the reading, whether they were asked questions or not.