concurring in the judgment.
I agree with the result reached in the court’s opinion. I do so because I agree that part-time work, including work that largely includes being “on call,” can constitute substantial gainful activity, and because I believe that the record supports the Secretary’s finding that Ms. Wright was engaged in substantial gainful activity, albeit only marginally. However, ■ I believe *685the case to be much closer than the court’s opinion reflects, and I write separately because I fear that the opinion may create the impression that part-time work (yielding a certain minimum amount prescribed by the Secretary’s regulations) automatically constitutes substantial gainful activity, thereby foreclosing meritorious disability claims of persons with serious mental illness who, by happenstance, are able to perform a specific marginal job.
I.
I note preliminarily that, although I agree that there is sufficient evidence to support the Secretary’s findings, I do not agree with the court’s opinion insofar as it says that there is no evidence, see ante at 683, to support psychologist Levine’s opinion that Ms. Wright was unable to perform substantial gainful employment. In fact, the only other professional to treat Ms. Wright, Dr. Stephanie Ward, also felt that she had serious mental disabilities that interfered with her ability to work. Dr. Ward, a psychiatrist, reported that the plaintiff displayed “chronic anxiety and angry, paranoid feelings, and claimed that she hated people.” Dist. Ct. Op. at 5 (July 28, 1989). Dr. Ward concluded that Wright’s ability to work and cope with other people was limited, despite the fact that she “appeared to function adequately” at her previous job. See ante at 677 (emphasis added).
Dr. Ward did not state that Ms. Wright functioned adequately at work, and there is no indication that Dr. Ward had sufficient information to make such an assessment. The person who did have that knowledge, Ms. Wright’s supervisor at Women Organized Against Rape, stated that Ms. Wright’s work was satisfactory. It is that opinion on which I would rely to conclude that the Administrative Law Judge’s finding that Ms. Wright was engaged in substantial gainful activity was not against the substantial weight of the evidence. See Universal Camera Corp. v. N.L.R.B., 340 U.S. 474, 491, 71 S.Ct. 456, 466, 95 L.Ed. 456 (1950); Brown v. Bowen, 845 F.2d 1211, 1213 (3d Cir.1988).
II.
It is important to emphasize that neither the fact that Ms. Wright’s earnings exceed the statutory guideline, 20 C.F.R. § 1574(b)(2)(vi) (1989), nor the fact that she worked enough hours to constitute more than part-time work, necessarily resolves the question whether she was engaged in substantial gainful activity. See Kangas v. Bowen, 823 F.2d 775 (3d Cir.1987); Markham v. Califano, 601 F.2d 533 (10th Cir.1979); Chiappa v. Secretary of Dept. of Health, Ed. and Welfare, 497 F.Supp. 356, 360 (S.D.N.Y.1980); Barats v. Weinberger, 383 F.Supp. 276 (E.D.Pa.1974) (all holding that a finding of substantiality is necessary notwithstanding the statutory presumptions with regard to earnings or hours worked). The Secretary’s own regulations indicate that an independent substantiality inquiry is appropriate:
While the time you spend in work is important, we will not decide whether or not you are doing substantial gainful activity only on that basis. We will still evaluate the work to decide whether it is substantial....
10 C.F.R. § 404.1573(e). Among the factors that the Secretary considers is whether “you are doing work that involved minimal duties that make little or no demands on you and that are of little or no use to your employer....” Id. § 404.1573(b).
Evaluating Ms. Wright’s work in light of this standard and the factfinding to which we owe deference, I cannot say that her on call duties had little or no value to her employer. Given her freedom from other responsibilities (children, school or dependent relatives), the demands made on Ms. Wright were not particularly onerous. Hence, she could perform her on call duties while doing “anything she wanted.” See ante at 677. However, other people may not have been as free as Ms. Wright was to put down whatever they were doing when they were on call. Thus, I think that Ms. Wright was performing a job that commanded a (relatively) significant salary because, notwithstanding her disability, she *686was able to perform a service — namely being available to get to the hospital to conduct an interview — that was in demand on the open market.
If there was evidence that Ms. Wright had performed the job inadequately, that she did not respond to her calls, or that she was incapable of interacting with the victims whom she did interview, I might vote differently, whether or not Women Organized Against Rape had continued to retain her. In such a case, the evidence might be, in effect, that payment over the statutory limit constituted an unwitting subsidy, making the situation more analogous to sheltered work (see 20 C.F.R. § 404.1574(a)(3)) than substantial gainful activity (see 20 C.F.R. § 404.1572(a)). Because, on the record before us, there is no evidence to that effect (Ms. Wright apparently performed the job in a satisfactory manner), I agree that the work that Ms. Wright performed for Women Organized Against Rape constituted substantial gainful activity. On these understandings, I concur in the judgment.