This chapter focuses on the assessment of the process of maturation from birth to childhood, that is, part of the total process that is intimately linked to physical growth. It is important, therefore, to differentiate between "growth" and "maturation." Development or maturation, on the other hand, is defined as "a progression of changes, either quantitative or qualitative, that lead from an undifferentiated or immature state to a highly organized, specialized, and mature state." The end-point of maturation, within the context of the growth, is the attainment of adulthood, which one defines as a "functionally mature individual."There are three methods of assessment, skeletal development, bone-specific scoring techniques, and the Rochee-Wainere-Thissen technique.