Infant and Toddler Development

infant and toddler development, the physical, emotional, behavioral, and mental growth of children from ages 0 to 36 months.

Different milestones characterize each stage of infant (0 to 12 months) and toddler (12 to 36 months) development. Although most healthy infants and toddlers reach each milestone within a specific window of time, there is much variation as to how wide that window may be. For example, culture, environment, socioeconomic status, and genetic factors can influence when an infant or toddler will begin to crawl, walk, or talk. Children who suffer from undernutrition, who lack social stimuli, or who lack access to proper health care may develop more slowly than children in more enriched environments. Concerns about infant or toddler development arise when milestones are absent or significantly delayed, since such situations may signal an underlying physical or mental condition. Identifying problems early in development is vital to a child’s health. Although parents are often the first to raise concerns, teachers and child care workers may spot problems that parents have not noticed or have been afraid to acknowledge. They may also be able to identify abused or neglected children who exhibit abnormal development.

Early in the 20th century, child development scholars began to understand that children were not just “small adults” but individuals with unique personalities and distinct needs. In the 1920s and ’30s Swiss psychologist Jean Piaget developed a theory that children’s cognitive abilities progress through four stages. According to Piaget, a sensorimotor stage characterized the first two years of life, during which time a child also becomes aware of the permanence of existence of objects in his or her environment. The work of Russian psychologist Lev S. Vygotsky, which reached English-speaking audiences around the same time as Piaget’s research, provided insight into how children think and develop language.

In 1933 the Society for Research in Child Development (SRCD) was established in the United States to apply new concepts in child development to improving the lives of the country’s children. The society initially focused on understanding how poverty and social deprivation affected development, with the aim of using that knowledge to design policies and programs to alleviate the negative effects of poverty. In 1964 U.S. Pres. Lyndon B. Johnson launched his War on Poverty, and in 1965 the U.S. Congress established the Head Start Program, which promotes “school readiness” for children from birth to five years. The program focuses its efforts on children from low-income families and offers health, nutritional, and social support to enrolled children and families.