The study assessed the cognitive development of preschoolers in Morogoro Municipality, Tanzania, focusing on early literacy, numeracy, and executive functions. Using the International Development and Early Learning Assessment (IDELA) tool, researchers evaluated 213 children from public and private schools. Results showed high performance overall, with numeracy scoring the highest (91% very high), followed by executive functions (81%) and literacy (53%). Older children and those in private schools outperformed peers in public schools, indicating the influence of resources, class size, and teaching methods. The study highlighted significant differences in cognitive skills based on age, school type, and gender, with girls excelling in literacy and executive functions. Recommendations emphasized improving resources, teacher training, and classroom conditions, especially in public schools, to bridge performance gaps. The findings underline the critical role of early education in fostering foundational cognitive skills for lifelong learning and academic success.