Pain can constitute a significant nonexertional impairment which precludes naked application of the Grid and requires use of a vocational expert. The medical-vocational guidelines are not dispositive of the status of persons whose exertional limitations are further complicated by other non-exertional ailments. The Secretary must engage in an "individualized analysis" to determine whether the combination of exertional and nonexertional impairments, in light of the claimant's age, education, and work experience, renders her disabled. Conflicts in the evidence are for the Secretary to resolve. Court suggests Secretary present "more specific expert evidence concerning [the claimant's] ability to function in the workplace, coupled with a vocational expert's testimony as to the availability of jobs in the national economy which someone possessing claimant's ... limitations might fill." Secretary not obliged to take claimant's assertions of disabling pain at face value.