A study investigated young children's knowledge of the constraint that prevents questioning from a position inside a temporal adjunct: i.e., knowledge of the ungrammaticality of a question such as "Who did Fred kiss Sue before hugging...?" Subjects were 30 children aged 3 to 5 years, who listened to stories accompanied by pictures and were asked potentially ambiguous questions in which the "wh-" word could be taken to refer to either the object of the main clause or the object of an embedded clause. Results indicate that children as young as 3 years old are aware of this "island" constraint, suggesting that they have movement in syntax and have, by this stage, formed a grammar similar to that of adults in one fundamental aspect. (MSE)