How is a developmental disability diagnosed?

Only qualified medical professionals can properly diagnose a developmental disability. Some conditions can be diagnosed before birth through medical testing. Others only manifest themselves when a child fails to meet developmental "milestones" like rolling over, crawling or learning to vocalize. Subsequent testing can often identify the source of the developmental delay but not always. Other forms of developmental disability can escape proper diagnosis altogether. People with Asperger's syndrome, for example, show no visible signs of a disability but often struggle socially.  A proper and early diagnosis in such cases is critical to the long-term well-being of the individual.