Turn-transition in adult conversation is remarkably precise, with a median close to zero milliseconds. This means one needs to predict the end of their interlocutor’s turn to come in on time. The interaction engine hypothesis (Levinson, 2006) suggests the ability to appropriately time turns in social interaction is realized early in development, before and independent of language. Few studies have assessed timing of turn-taking in infant development. We analyzed video-recordings of 12 mother-infant dyads at 12 and 18 months in free-play interactions. Findings indicate that in the first half of the second year of life infants become more skilled in taking turns in vocal exchanges as evidenced by decreasing onset times of their turns (median = 700ms at 18 months) as well as a decrease in number of onsets produced in overlap with their mothers, which at 18 months is at the maternal level of overlapping onsets produced (20%).