Dramatic changes occur in the areas of physical, cognitive and executive function, language and literacy, and socio-emotional development between the ages of 3 to 8, when most children in the world are in preschool and primary school. By preschool age, most children can follow directions of the teacher, understand numbers and words and speak sentences, manipulates small toys, represent one thing by another, feel empathy and guilt, and be bilingual, but are still small physically and young cognitively. In terms of physical development, the focus will be on fine and gross motor skills which improve greatly during this period, issues with growth, particularly height and weight, and under-five mortality. Stunting and malnutrition rates over time are cited, and particularly the 50 percent decrease in under-five mortality (U5MR) from 1990 to 2013. it indicates that the MDGs, which had a goal of reducing U5MR by two-thirds, may have made a large difference although the problem continues to be concentrated in certain regions of the world. The chief immediate causes are major health problems of early childhood including pneumonia and diarrhea, which are predicted by social determinant that include poverty and access to sanitation. Greater resources and finances are needed to fulfill globally-set goals for children.