Developmental milestones are skills such as taking a first step, smiling for the first time, and saying a first word. We have expected milestones for children related to motor skills (e.g., crawling, walking), talking, playing, behaving, and learning. Click here to test your knowledge of developmental milestones.

Developmental monitoring can be done by anyone involved in the care of a young child and simply means noting specific ways a child plays, learns, speaks, acts, and moves every day. Most often, a child's growth and development are kept track of through a partnership between parents and their doctor/healthcare professional. Developmental monitoring often involves tracking a child's development using a checklist of developmental milestones. At each well-child visit, the parents and doctor talk about these milestones and any concerns.

Developmental screening is a more formal process that uses a validated screening tool at specific ages to determine if a child's development is on track or whether he or she needs to be referred for further evaluation. The American Academy of Pediatrics recommends that all children be screened at 9 months, 18 months, and 24 or 30 months of age. Parents can ask their child's doctor to conduct a screening test at any time. Health professionals might use screening procedures, which include interviewing caregivers, providing caregivers with rating forms to fill out, or observing and interacting with a child to see how he or she learns, communicates, and behaves. For more information regarding developmental screening, please refer to the CDC's Developmental Screening Fact Sheet.

A child exhibits a developmental delay when he or she does not reach a developmental milestone expected for his or her age. It is important for caregivers to pursue additional developmental screening and evaluation when a child has a developmental delay, as delays might be indicative of a developmental disability or other problem and a child may qualify for and benefit from early intervention services.

A developmental disability is a chronic condition that is present during early development and usually lasts throughout a person's life. Estimates in the United States show that approximately one in six children has one or more developmental disabilities, such as autism spectrum disorder, attention deficit hyperactivity disorder (ADHD), intellectual disability, cerebral palsy, hearing loss, vision impairment, or learning disability. Most intellectual/developmental disabilities are thought to be caused by a combination of possible factors, such as genetics, prenatal exposure to alcohol, prenatal or early childhood exposure to infections, and prenatal or early exposure to environmental toxins, such as lead. For many developmental disabilities, the exact cause is unknown. Please visit the CDC's developmental disabilities webpage for more information.

Autism spectrum disorder (ASD) is a developmental disability characterized by persistent impairments in social interactions and communication, as well as restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. Toddlers and preschoolers with impairment in social and communication skills may be less responsive in social interactions, have delayed language skills, and demonstrate impairments related to nonverbal communication behaviors, such as gestures and eye contact. Additionally, children with ASD often exhibit repetitive movements, behave in a highly rigid manner, or have unusual or overly intense interests. For more information regarding early warning signs of ASD, click here.