The purpose of this study was to perform a sequential analysis of private and social speech in children's dyadic communication. To investigate the communication patterns, a category system was applied to the communication of 64 paired third (M = 8 years and 8 months) and fifth (M = 10 years and 8 months) graders, while playing with a Lego-set (construction material). The results revealed that: (a) at both grades, when one child addresses the other child about the task, it is highly probable that the latter will address the first child immediately afterwards and will adapt to task-related semantic content; (b) at both grades, children's private speech about the task stops them from communicating a task-related production to their partner immediately afterwards; (c) at third grade, task-relevant private speech favors the prolongation of the break in interpersonal communication and the use of inner speech by both children; and (d) at fifth grade, children are more able to distinguish private speech from social speech than at third grade.