Exceptional learners is the term used in the United States to refer to students with disabilities (as well as those who are gifted and talented). The majority of students with disabilities have cognitive and/or behavioral disabilities, that is, specific learning disability (SLD), intellectual disability (ID), emotional disturbance, (ED), attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD). The remaining have primarily sensory and/or physical disabilities (e.g., blindness, deafness, traumatic brain injury, cerebral palsy, muscular dystrophy). Many of the key research and policy issues pertaining to exceptional learners involve their definitions and identification. For example, prior to SLD being formally recognized by the U.S. Department of Education in the 1970s, its prevalence was estimated at approximately 2% to 3% of the school-age population. However, the prevalence of students identified for special education as SLD grew rapidly until by 1999 it reached 5.68% for ages 6 to 17 years. Since then, the numbers identified as SLD has declined slowly but steadily. One probable explanation for the decrease is that response to intervention has largely replaced IQ-achievement as the method of choice for identifying SLD. The term intellectual disability has largely replaced the classification of mental retardation. This change originated in the early 2000s because of the unfortunate growing popularity of using retard as a pejorative. Although ID used to be determined by a low IQ-test score, one must also have low adaptive behavior (such as daily living skills) to be diagnosed as ID. That is the likely reason why the prevalence of students with ID at under 1% is well below the estimated prevalence of 2.27% based solely on IQ scores two standard deviations (i.e., 70) below the norm of 100. There are two behavioral dimensions of ED: externalizing (including conduct disorder) and internalizing (anxiety and withdrawal) behaviors. Research evidence indicates that students with ED are underserved in public schools. Researchers have now confirmed ADHD as a bona fide neurologically based disability. The American Psychiatric Association recognizes three types of ADHD: (a) ADHD, Predominantly Inattentive Type; (b) ADHD, Predominantly Hyperactive-Impulsive Type; and (c) ADHD, Combined Type. The American Psychiatric Association recognizes two types of ASD: social communication impairment and repetitive/restricted behaviors. The prevalence of ASD diagnosis has increased dramatically. Researchers point to three probable reasons for this increase: a greater awareness of ASD by the public and professionals; a more liberal set of criteria for diagnosing ASD, especially as it pertains to those who are higher functioning; and “diagnostic substitution”—persons being identified as having ASD who previously would have been diagnosed as mentally retarded or intellectually disabled. Instruction for exceptional children, referred to as “special education,” differs from what most (typical or average) children require. Research indicates that effective instruction for students with disabilities is individualized, explicit, systematic, and intensive. It differs with respect to size of group taught and amount of corrective feedback and reinforcement used. Also, from the student’s viewpoint, it is more predictable. In addition, each of these elements is on a continuum.