In clinical diagnostic and functional development, special needs (or additional needs) refers to individuals who require assistance for disabilities that may be medical, mental, or psychological. Guidelines for clinical diagnosis are given in both the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases 9th edition. Special needs can range from people with autism, cerebral palsy, Down syndrome, dyslexia, dyscalculia, dyspraxia, dysgraphia, blindness, deafness, ADHD, and cystic fibrosis. They can also include cleft lips and missing limbs. The types of special needs vary in severity, and a student with a special need is classified as being a severe case when the student's IQ is between 20 and 35. These students typically need assistance in school, and have different services provided for them to succeed in a different setting.

In the United Kingdom, special needs usually refers to special needs within an educational context. This is also referred to as special educational needs (SEN) or special educational needs and disabilities (SEND). In the United States, 19.4 percent of all children under the age of 18 (14,233,174 children) had special health care needs as of 2018.

The term is seen as a dysphemism by many disability rights advocates and is deprecated by a number of style guides (e.g. APA style).