Research Findings: This study examined the relation between early childhood education (ECE) participation and early child development in Myanmar. It considered whether this relation varied by ethnic group, language(s) spoken at home, and language(s) of ECE instruction. Participants were 1,494 children (759 girls) from Myanmar, aged between 36 and 71 months. Children were directly assessed using the East Asia-Pacific Early Child Development Scales. ECE participation was associated with higher composite developmental scores and higher scores across 7 domains, and ethnic group did not moderate ECE-development associations. ECE dosage of between 12 and 18 months was associated with the highest developmental scores. For ethnic minority children, minority-language ECE instruction was associated with higher developmental scores regardless of language(s) spoken at home, but Myanmar-language ECE instruction was associated with higher developmental scores only for children also exposed to Myanmar at home. Practice or Policy: Findings highlight the benefits of ECE participation for the holistic development of both ethnic majority and minority children. The policy of ECE programme expansion in Myanmar may be delivering benefits to children's development, but further efforts may be needed to deliver language support for ethnic minority children not exposed to Myanmar language at home.