The positive links between children's theory of mind (ToM), emotion understanding, and positive peer relationships are well established. However, the existing literature lacks comprehensive studies investigating the longitudinal interplay between these components in preschool-aged children. This study aimed to fill this gap by examining the concurrent and longitudinal associations between young children's social cognition and their positive peer relationships at three different time points over the course of 7 months. A sample of 211 preschool children (age in months: M[subscript T1] = 43.2, SD[subscript T1] = 6.6) underwent standardized assessments evaluating their ToM and emotion understanding, while playgroup educators reported on children's positive peer relationships. Using multivariate latent growth modeling, we expected to find that higher levels of ToM and emotion understanding would be associated with a greater rate of change in positive peer relationships and that higher levels of positive peer relationships would be associated with a higher rate of change in ToM and emotion understanding. Contrary to our expectations, the results did not support the anticipated longitudinal associations. Nevertheless, a noteworthy correlation emerged between children's emotion understanding and positive peer relationships at T1, in line with previous research and social-constructivist theories.