Using the negated universal quantifier not every, the study investigates the interpretations of scalar implicatures, lexical presuppositions, and implicated presup- positions by Thai children with autism spectrum disorders (ASDs; n = 32), compared to their typically-developing (TD) peers (n = 70) and adults (n = 40). The results provide further empirical evidence to the literature (Chevallier et al. 2010, Hochstein et al. 2017, Pijnacker et al. 2009) that not only do adolescents with ASD perform on par with TD adolescents, children with ASD are also age-appropriate in their performance on deriving scalar implicatures. Despite the children with ASD’s ability to compute scalar implicatures, they still tend to give more logical, literal responses, compared to their peers. Compared to adults, both children with ASD and TD children still have a higher tendency to rely on the logical meaning rather than pragmatically inferred meaning. No additive effects of implicated presuppositions are found in any group of the participants.