Five-to-six-year-olds' abilities to detect and solve ambiguities in spoken language have been found to be a predictor of their later reading abilities in first-to-third grade. However, the origins of this relationship remain unclear. Success in ambiguity detection may be reflective of overall language attainment, which varies with socioeconomic status (SES) and is known to predict reading. Yet, it is also possible that children's ability to detect ambiguity is explained by domain-general cognitive control skills, which can also vary with SES and predict literacy attainment. In this cross-sectional study, we examined within the same children the contributions of overall language knowledge, SES, and cognitive control skills to their ability to detect ambiguities in speech. Five-to-six-year-old French-learning preschoolers (n = 38) performed three different tasks: ambiguity detection, a cognitive control (Flanker/No-Go) task, and standard assessments of vocabulary and oral language comprehension in French (BSEDS). Years of maternal education after the end of high school were used as a proxy of family SES. Individual differences in the ability to detect ambiguity were strongly related to children's cognitive control abilities, as indexed by congruency effects in the Flanker task. No relations with SES or language assessment were observed. These results lend support to the idea that children's reading development may hinge upon their ability to deal effectively with temporary lexical, syntactic, and semantic ambiguities that pervade real-time sentence interpretation and that their ability to deal with representational conflict in speech is reflective of their domain-general cognitive control skills.