A randomized controlled parallel-group trial was conducted to investigate the effectiveness of two 10-week early childhood education and care (ECEC) interventions "SAGA" and "Pikkuli" for supporting social-emotional and verbal development. All children above the age of 4 were invited from 15 Finnish volunteer ECEC groups (n SAGA = 52, n Pikkuli = 56, n control group = 42). The children and caregivers, but not the personnel (who carried out the intervention), were blinded to the group assignment. Children in the SAGA intervention advanced in prosocial behavior and social orientation and had fewer internalizing and externalizing problems after the intervention. Children in the Pikkuli intervention advanced in prosocial behavior and had fewer internalizing problems after the intervention. There were no significant changes in any of the aforementioned outcomes in the control group. The results suggest that both interventions have good potential in supporting children's social-emotional development in the ECEC environment.