Adaptive behavior generally refer to an individual's ability to effectively meet social and community expectations for personal independence, maintenance of physical needs, acceptable social norms, and interpersonal relationships. Competence in areas of functional independence can be expected to change with age or developmental stage.

Problems in acquiring adaptive behavior can occur at all levels from early life to adulthood in:
  1. developing and mastering basic maturational skills (such as talking, walking, or toileting)
  2. learning academic skills and concepts
  3. making social and vocational adjustments.
Since functional independence is socially defined, an individual's performance must be considered within the context of the environments and social expectations that affect his or her functioning.

Adaptive behaviors are skills that a person learns in the process of adapting to his/her surroundings. Since adaptive behaviors are for the most part developmental, it is possible to describe a person’s adaptive behavior as an age equivalent score. A typical five-year-old, for example, would be expected to have adaptive behavior similar to that of other five-year-olds.
The ICAP has 77 adaptive behavior items divided into four areas: Motor Skills; Social and Communication Skills; Personal Living Skills; and Community Living Skills.

Each ICAP adaptive behavior item is a statement of a task (for example: "Washes, rinses, and dries hair").
  • Never or rarely does well, even if asked
  • Does, but not well (or 1/4 of the time)
  • Does fairly well (or 3/4 of the time)
  • Does well without being asked
The respondent rates the subject on each task, using a scale from 0 to 3. This scale assesses the quality of performance and the individual's motivation. That is, even though someone may be able to perform a task, he/she may not do so independently, either because he does not realize that it is necessary to do so, or because he refuses to (a behavior problem).

From infant to adult levels, the ICAP yields highly accurate adaptive behavior scores that include age equivalent, percentile rank, standard scores, and others.