This paper aims to determine possible gender differences in children's observed emotional expressions and their relationship with teacher-rated self-regulation (SR) skills in the setting of early childhood education and care (ECEC). Supporting SR and emotional wellbeing in early childhood can be considered a favourable pathway towards holistic development (e.g. Shonkoff et al. [2012]. The lifelong effects of early childhood adversity and toxic stress. "Pediatrics," 129(1), e232-e246; Bagdi & Vacca [2005]. Supporting early childhood social-emotional well being: The building blocks for early learning and school success. "Early Childhood Education Journal," 33(3), 145-150). The participants included 1213 (44.2%) boys and 1075 (41.0%) girls which were 13-83 months old. The SR data was collected through an evaluation instrument. Emotional expressions (N = 50480) were observed with an independent instrument. The results indicated how girls were observed to have more "neutral," "calm" or "peaceful"-related emotional expressions, while boys tended to express more "surprise," "curiosity," "anger" or "frustration"-related emotions. Boys' and girls' ability for SR was related to their emotional expressions. Boys' and girls' SR skills had the same tendency in weak, moderate and good SR categories.