Using a longitudinal design, preschoolers’ appreciation of a listener’s knowledge of the location of a hidden sticker after the listener was provided with an ambiguous or unambiguous description was assessed. Preschoolers (N = 34) were tested at 3 time points, each 6 months apart (4, 4½, and 5 years). Eye gaze measures demonstrated that preschoolers were sensitive to communicative ambiguity, even when the situation was unambiguous from their perspective. Preschoolers’ explicit evaluations of ambiguity were characterized by an initial appreciation of message clarity followed by an appreciation of message ambiguity. Children’s inhibitory control skills at 4 years old related to their explicit detection of ambiguity at later ages. Results are discussed in terms of the developmental progression of preschoolers’ awareness of communicative ambiguity.