District Court erred by reweighing the evidence. The resolution of conflicting evidence is solely within the province of the Secretary and the District Court is required to accept as conclusive the Secretary's determination, if supported by substantial evidence.

20 CFR §404.970, which lists four situations in which AC will review a case, is not an exhaustive list of all situations where Appeals Council may take review. Restrictive interpretation of AC's right to own motion review could interfere with administration of claims and monitoring of department. An ALJ's decision to give or deny credit to a particular witness's testimony should not be reversed absent an adequate explanation of the grounds for the reviewing body's source of disagreement with the ALJ. Court reverses where Appeals Council, on own motion review, finds no severe impairment but fails to state reasons for rejecting ALJ's credibility determination.

Discussion of observable signs of pain. ALJ under no duty to go to "inordinate lengths to develop a claimant's case." Holding that Secretary is not at the mercy of every claimant's subjective assertions of pain applies equally well to subjective claims of dizziness. Claimant must show that her impairment is "medically determinable" and only in a rare case can she do this without medical evidence.