The PlayMatters baseline study in Tanzania used the International Development and Early Learning Assessment (IDELA) to measure the developmental progress of children in refugee and host communities. IDELA assessed domains such as emergent literacy, numeracy, fine motor skills, socio-emotional development, and executive function among children aged 3-6. Results indicated that refugee children performed better overall compared to host community children, with statistically significant differences in emergent literacy, socio-emotional development, executive function, and approaches to learning. Refugee children scored highest in socio-emotional development (49%) and executive function (51%), compared to 32% and 38%, respectively, for host children. However, foundational skills like literacy and numeracy lagged behind, with average scores below 33%. The assessment revealed gender-based disparities, with boys outperforming girls in some domains. These findings emphasize the need for targeted interventions to strengthen literacy and numeracy skills and ensure equitable development outcomes across all groups.