Functional limitations include having difficulty lifting something as heavy as 10 pounds (such as a full bag of groceries), walking up 10 steps without resting, walking a quarter of a mile (about 3 city blocks), standing for about 20 minutes, bending down from a standing position to pick up an object from the floor, reaching up over the head or reaching out as if to shake someone's hand, using fingers to grasp or handle something (such as picking up a glass from a table), or holding a pen or pencil.

In 1994 and 1995, this variable is part of the Disability Supplement (NHIS-D) that collects information on disability. NHIS-D included two household interviews: in Phase I all members of sample families were screened for any indication of disability; in Phase II persons with any indication of disability were followed-up for additional information. Phase I includes sensory, communication, and mobility problems; health conditions; activities of daily living and independent activities of daily living; functional limitations; mental health; services and benefits; special health needs of children; early child development; education; relationship to respondent; and perceived disability. Phase II includes four Disability Followback Survey (DFS) questionnaires: one for children, one for adults, one for elderly persons (69 years of age and over) without any indication of disability (also called the Supplement on Aging or SOA; only in 1994), and one for persons with a history of polio.