Using the methods of conversation analysis, the opening sequences of a map task in the interactions of sixteen children aged seven to twelve were analyzed. The analytical concerns driving the study were who started, how they started, and how children dealt with differential access to information and the identification of phases within the opening. It was found that all participants oriented to the instruction-giver as the one to start, even when the information-follower commenced the task. With respect to how to start, the older children produced a question and answer sequence or a try-mark to establish a common starting point. Five of the eight younger children inferred a common starting point on the map. Three recurring phases were identified: readiness to begin established through a discourse marker, location of the starting point, and actual instruction. The findings are discussed with reference to the importance of interaction in referential spatial tasks.