Despite being the largest archipelago and the fourth populous country in the world, Indonesia has received limited research attention to the socioemotional development of its diverse child populations. As the corona virus 2019 (COVID-19) pandemic significantly interrupted the life of individuals and families all over the world, it is also critical time to better understand the status and need of Indonesian young children's socioemotional development to inform corresponding practices and policies. This study investigated the differences in Indonesian preschoolers' socioemotional competencies between the pre-pandemic and pandemic periods, as well as across three representative provinces of DKI Jakarta, DI Yogyakarta, and West Java. Teachers of 546 preschoolers aged 3 to 6 years old (M = 4.94, SD = 0.88, 51.3% male) were collected on children's self-regulation, emotion and expression, and social interaction before and during the pandemic and across the three provinces. Research Findings: Results indicated significantly worse socioemotional competencies of preschoolers during the pandemic in comparison to the pre-pandemic period. In addition, preschoolers from DKI Jakarta displayed significantly worse socioemotional competencies than their counterparts from the other two provinces. Practice or Policy: Findings highlighted the socioemotional challenges that Indonesian preschoolers encountered during the pandemic as well as the heterogeneity embedded in diverse Indonesian children's development. Implications for parenting and interventions were generated to reduce children's socioemotional challenges and to support their development.