OPINION OF THE COURT
Laurel Reefer appeals a decision discontinuing her Social Security benefits. Because that decision was not supported by substantial evidence, we reverse and remand.
I. Background
In 1989, Reefer began receiving Social Security Supplemental Security Income (“SSI”) benefits because she suffered disabling hypertension. In March 1997, the Social Security Administration (“SSA”) reviewed Reefer’s case and issued a notice of disability cessation on the ground that her medical condition had improved to the *378 point that her disability had ceased. 1 Her benefits were discontinued as of May 31, 1997.
Reefer requested reconsideration of the SSA’s denial of benefits, alleging continuing disability due to hypertension, anxiety, tiredness, muscle spasms and pain in her left leg, shoulder, arm and hand, chest pains, neck pains and headaches. On reconsideration, the SSA again denied Reefer benefits. She then sought an administrative hearing, which was held on September 10, 1998 before an administrative law judge (the “ALJ”). Reefer appeared pro se at the hearing, which lasted only twenty minutes. She testified that she suffered a stroke in 1997 and provided the ALJ with the names of her two treating physicians - Dr. Tuchinda, a cardiologist, and Dr. Tabas, her primary-care physician. She also testified that she was having seizures, for which her neurologist ordered video monitoring. At the conclusion of the hearing, the ALJ said that he would obtain additional medical records and, if necessary, would call for another hearing. The ALJ did obtain some of Reefer’s medical records. However, he issued his opinion without the benefit of a second hearing and without requesting testimony from either of Reefer’s treating physicians. The record before the ALJ contained no medical report concerning the 1997 stroke.
Between the date of the hearing and the ALJ’s decision, Reefer underwent elective surgery in 1999 to remove pressure from her brainstem. Following this surgery, she suffered a second stroke. However, because the ALJ did not request medical records detailing these events, they also were not before him at the time of his decision. Reefer submitted those records both to the District Court and to this Court on appeal. 2
In his May 26, 1999 decision, the ALJ found that Reefer was not entitled to SSI. First, the ALJ found that Reefer does not suffer from any of the impairments described in 20 C.F.R., Pt. 404, Subpt. P, App. 1, which would make her per se disabled. He said that her “hypertension!,] though severe, is well-controlled ... with only situational episodic elevation,” and that no medical evidence supported her alleged mental and neurological impairments. He also found that Reefer’s “activities of daily living are ... not consistent with an individual experiencing total! ] disability,” and that her “statements concerning her impairments and their impact on her ability to work are not entirely credible.” In so finding, the ALJ noted that “[i]n her Daily Activities Questionnaire, the claimant indicated that she can independently care for her personal needs. She cooks, does dishes, dusts, vacuums, and does other housework.” The ALJ went on to find that “[ajlthough she indicated on her Fatigue and Pain Questionnaires that both pain and fatigue interfere substantially with her daily activities, this is not supported by her own statements, nor by the objective medical evidence in *379 record.” Finally, the ALJ stated that “the claimant retains the residual functional capacity to perform the exertional demands of at least light work, or work which requires maximum lifting of 20 pounds and frequent lifting of up to 10 pounds.... The evidence supports a finding that she is able to lift and carry 20 pounds. The claimant has no significant non-exertional limitations which narrow the range of work she can perform, as demonstrated by the objective medical evidence.”
In this context, the ALJ concluded that Reefer was capable of returning to her past relevant work as a cleaner. The ALJ also noted that application of Reefer’s residual functional capacity to the Medical-Vocational Guidelines set out in 20 C.F.R., Pt. 404, Subpt. P, App. 2, confirmed that there are jobs in the economy she can perform.
Reefer filed a request for review, which the Appeals Council denied. She then filed a complaint in the District Court, which granted summary judgment in favor of the Commissioner. At issue here is whether the ALJ’s determinations that Reefer is no longer disabled and can find work in the economy are supported by substantial evidence. Reefer asks that we either (1) reverse the District Court’s decision and grant her SSI benefits or (2) remand the claim to the ALJ for additional testimony and related proceedings.
II. Jurisdiction and Standard of Review
We have subject matter jurisdiction pursuant to 42 U.S.C. § 405(g). Appellate jurisdiction exists under 28 U.S.C. § 1291.
We examine the record to determine whether substantial evidence supported the ALJ’s findings.
Smith v. Califano,
The “substantial evidence” standard of review requires that we review the whole record.
Smith,
III. Discussion
We reverse for two reasons. First, the ALJ did not adequately develop the record, a duty he owed Reefer because she appeared pro se. Second, he neglected to explain why he credited some record evidence but rejected other evidence. In this context, we find that substantial evidence does not support the ALJ’s opinion.
*380 A. The ALJ failed adequately to develop the record.
An ALJ owes a duty to a
pro se
claimant to help him or her develop the administrative record. “When a claimant appears at a hearing without counsel, the ALJ must ‘scrupulously and conscientiously probe into, inquire of, and explore for all the relevant facts.’ ”
Key v. Heckler,
While we do not prescribe any particular procedures that an ALJ must follow,
see Vt. Yankee Nuclear Power Corp. v. Natural Res. Def. Council, Inc.,
Second, while the ALJ found Reefer’s “statements concerning her impairments and their impact on her ability to work ... not entirely credible,” he had an insufficient basis to make this conclusion. We would ordinarily defer to an ALJ’s credibility determination because he or she has the opportunity at a hearing to assess a witness’s demeanor.
See, e.g., Atl. Limousine, Inc. v. NLRB,
Moreover, Reefer’s medical records reflect that she consistently complained to her treating physicians about pain, body tremors leading to stumbling, dizzy spells, nausea, and headaches. Those records also reflect that Reefer underwent a cranial CT scan because she experienced fre
*381
quent headaches. That scan indicated possible abnormalities. The January 4, 1999 evaluation of Reefer by Dr. Baraff (a neurologist) was inconclusive, but he was unsure whether she might have an intra-cranial aneurysm, partial seizures, or migraines. Having seen these complaints in the medical record, the ALJ was not at liberty to ignore them. Rather, he had a duty to consider seriously Reefer’s subjective complaints of pain and to probe further.
See Baerga v. Richardson,
Finally, while the ALJ did request certain of Reefer’s medical records, he did not have before him medical records from 1999 as well as correspondence addressed to one of Reefer’s treating physicians. These records discuss the surgery to remove pressure from her brainstem as well as her 1999 stroke. That the ALJ did not arrange with Reefer’s treating physicians to receive them suggests that his document request was too narrow in scope. We need not decide whether the ALJ’s failure to obtain these 1999 records, without more, provides a reason for remand
3
because we believe that remand is otherwise warranted.
See Dobrowolsky,
B. The ALJ failed to explain why he credited some evidence and discredited other evidence.
The ALJ concluded that “the claimant’s hypertension has been essentially well-controlled with medication since 1995, with only situational episodic elevation.” In so concluding, he insufficiently explained numerous blood pressure readings and treating physicians’ comments that suggested otherwise.
See Fargnoli v. Massanari,
Also, in determining Reefer’s residual functional capacity for work, the ALJ did not explain why he chose to credit one medical report over another.
See Fargnoli,
Despite these inconsistent evaluations {e.g., Dr. Stevens stated that Reefer could carry 10 pounds only occasionally while the state agency physician stated she could carry 50 pounds occasionally and Dr. Baraff said that her carrying ability was unaffected by her impairment), the ALJ concluded that Reefer “retains the residual functional capacity to perform the exertional demands of at least light work, or work which requires maximum lifting of 20 pounds and frequent lifting of up to 10 pounds.... The evidence supports a finding that she is able to lift and carry 20 pounds.” In so holding, the ALJ disregarded Dr. Stevens’s contrary report without explaining why he did so, thereby ignoring our mandate in Fargnoli Accordingly, remand is required.
IV. Conclusion
Because of the deficiencies in the ALJ’s determination, the District Court erred in affirming it. The ALJ faded to develop the record adequately in this pro se case. In assessing Reefer’s residual functional capacity for work, he also failed to explain why he credited certain medical reports and not evidence more favorable to Reefer. We therefore reverse and remand so that the District Court may remand to the ALJ with directions to address these issues. In so doing, the ALJ also should examine records relating to Reefer’s 1999 stroke.
Notes
. 42 U.S.C. § 423(f)(1) states that a benefit recipient may be deemed ineligible for benefits if it is determined that his or her disability has ceased, when that determination is supported by substantial evidence of medical improvement and the claimant is able to engage in substantial gainful activity. 20 C.F.R. § 416.994(b)(5) provides a seven-step test under which termination-of-benefits inquiries are to be conducted.
. Because these records were not before the ALJ, the Commissioner argues that we may not consider them in determining whether the ALJ's decision was supported by substantial evidence.
Matthews v. Apfel,
. "[E]vidence first presented to the district court [and not to the ALJ] must not only be new and material but also be supported by a demonstration by claimant of 'good cause for not having incorporated the new evidence into the administrative record.' ”
Matthews v. Apfel,
