"Good cause" for remand due to Secretary's failure to develop record. ALJ is not at liberty to substitute his own impression of an individual's health for uncontroverted medical opinion. Given unchallenged diagnosis of chronic schizophrenia, coupled with uncontradicted testimony concerning claimant's degeneration in recent years and evidence of gross interference with his interpersonal relations, finding of no severe impairment was not supported by substantial evidence. If Secretary is doubtful as to severity of claimant's mental disorder, appropriate course is to request a consultative evaluation, not to rely on the lay impressions of the ALJ. ALJ incorrectly applied "Listing" standard at Step 2. Certain mental abilities are a prerequisite to working: the regulations suggest as prerequisite to working: the ability to understand, carry out and remember simple instructions, to use sound judgment, to respond appropriately to supervision, co-workers and usual work situations and to deal with changes in a routine work setting. While claimant bears the burden of proof on the issue of disability, the Secretary nonetheless retains a certain obligation to develop an adequate record from which a reasonable conclusion can be drawn.

Dysthymic disorder is severe impairment. To determine the severity of a mental impairment, an ALJ must rate the degree of functional loss in four areas that the SSA has identified as essential to work: 1) activities of daily living; 2) social functioning; 3) concentration, persistence, or pace; and 4) deterioration or decompensation in work or work- like settings. Substantial evidence did not support ALJ's finding of a non-severe mental impairment where medical advisor's uncontradicted assessment that claimant had moderate restrictions in activities of daily living. Substantial evidence did not support ALJ's finding of a non-severe mental impairment where medical advisor's uncontradicted assessment that claimant had moderate restrictions in activities of daily living.

Step 2 (sequential evaluation) severity requirement is hereinafter to be a de minimus policy, designed to do no more than to screen out groundless claims. Various non-severe impairments viewed in combination may be disabling. SSR 85-28. See "severity" for discussion. Various non-severe impairments viewed in combination may be disabling.

ALJ is not at liberty to substitute her own opinions of an individual's health for uncontroverted medical evidence. ALJ erred in discrediting IQ scores where such test results are the only evidence on the point before the ALJ. It was error for ALJ to conclude that IQ score of 63 must be invalid because claimant had a work history. An IQ score of 63 and a steady work history are not necessarily incompatible. Claimant's work-related functions only became significantly limited when she developed a physical impairment in addition to her mild mental retardation. Under the mental retardation listings for adults, the lowest I.Q. score is to be used in determining whether an adult claimant meets the listing. If claimant's IQ is between 60 and 69, listing 12.05 requires an additional impairment imposing "additional and significant work-related limitation of function," which means that "its effect on a claimant's ability to perform basic work activities is more than slight or minimal." An impairment that meets the severity standard of the sequential evaluation a fortiori satisfies the significant limitations standard.

ALJ adequately developed record for pro se claimant. ALJ used correct standard for assessing severity.