The aim of this research was to develop a new observation-based measure for assessing caregivers' mind-mindedness in the preschool years and investigate whether this measure could explain the link between mothers' early appropriate mind-related comments and children's later mentalizing abilities. The new measure was developed using a sample of mothers and 44-month-olds (N = 171), characterizing mind-mindedness in terms of (a) solicited child involvement, (b) adaptive communication, and (c) internal state talk. These indices were positively related to established assessments of mind-mindedness at 8, 44, and 61 months. Positive associations were also observed with children's later mentalizing abilities. The new measure of mind-mindedness did not, however, mediate the relation between mind-mindedness in the first year of life and children's mentalizing abilities.