We examined whether and how the degree of meaning overlap between morphologically related words influences sentence plausibility judgment in children. In two separate studies with kindergarten and second-graders, English-speaking and French-speaking children judged the plausibility of sentences that included two paired target words. Some of these word pairs were morphologically related, across three conditions with differing levels of meaning overlap: low (wait-waiter), moderate (fold-folder) and high (farm-farmer). In another two conditions, word pairs were related only by phonology (rock-rocket) or semantics (car-automobile). Children in both ages and languages demonstrated higher plausibility scores as meaning overlap increased between morphologically related words. Further, kindergarten children rated sentences that included word pairs with phonological overlap as more plausible than second-grade children, while second-grade children rated those with high meaning overlap as more plausible than kindergarten children. We interpret these findings in light of current models of morphological development.