MEMORANDUM **

Rosemary Contreras appeals an adverse grant of summary judgment upholding the Commissioner of Social Security’s denial of her application for disability insurance benefits under Title II of the Social Security Act. We reverse and remand.

We review de novo a district court’s order affirming the denial of social security benefits and set aside the denial “only if it is not supported by substantial evidence or is based on legal error.” Bray v. Comm’r of Soc. Sec. Admin., 554 F.3d 1219, 1222 (9th Cir. 2009) (quotations omitted). “Substantial evidence ... is such relevant evidence as a reasonable mind might accept as adequate to support a conclusion.” Id. (quotations omitted). Because the factual and procedural background is familiar to the parties, we will not recount it here.

Contreras contends that the administrative law judge (“ALJ”) erred at step two of the five-step disability inquiry in finding that the fibromyalgia diagnosis of her treating physician, Dr. Dixit, was not “medically determinable.” We agree. An ALJ must provide “specific and legitimate” reasons for discounting the contradicted opinion of a treating physician. Lester v. Chater, 81 F.3d 821, 830 (9th Cir. 1995). That standard is not satisfied here.

The only rheumatologist to examine Contreras, Dr. Dixit, diagnosed the disease and documented sufficient clinical findings to support his diagnosis. Although Dr. Dixit’s notes do not identify the number or location of any specific tender points, he diagnosed Contreras in February 2002 “after a full history and physical examination” with fibromyalgia. In June 2003, Dr. Dixit indicated that Contreras “struggles on daily basis with severe fatigue, depression, increase in migraines, and multiple tender points throughout the body.” Three months later, he wrote that Contreras was “disabled” by her fibromyalgia. In April 2005, Dr. Dixit observed that Contreras had tender points in a “widespread distribution” satisfying the “ACR criteria for fibromyalgia.”

The testimony of non-examining physician Dr. Minor does not provide substantial evidence for the ALJ’s holding. Dr. Minor initially testified that the fibromyal-gia diagnosis was “consistent” with Contreras’s history and records and merely conceded on questioning that Dr. Dixit had not specified the number or location of her tender points. Dr. Minor did not have access to Dr. Dixit’s April 2005 notation *658 that Contreras satisfied the ACR criteria for fibromyalgia. Moreover, this Court has not required documentation of a fibro-myalgia diagnosis at that level of specificity. See Benecke v. Barnhart, 379 F.3d 587, 590, 594 (9th Cir. 2004) (holding that an ALJ errs in requiring objective evidence for a disease such as fibromyalgia that “is diagnosed entirely on the basis of patients’ reports of pain and other symptoms” and “that eludes such measurement”).

While several consultative examining ánd non-examining physicians declined to diagnosis fibromyalgia, a “rheumatologist’s opinion is given greater weight than those of ... other physicians because it is an ‘opinion of a specialist about medical issues related to his or her area of specialty.’ ” Id. at 594 n. 4 (quoting 20 C.F.R. § 404.1527(d)(5)). Specialized knowledge is “particularly important with respect to a disease such as fibromyalgia that is poorly understood within much of the medical community.” Id. Accordingly, we conclude that the ALJ erred in finding Contreras’s fibromyalgia diagnosis not “medically determinable.” We do not — and need not— address any other issue raised by the parties.

In light of the discussion above, we reverse the judgment of the district court, with instructions to remand this case to the agency for a redetermination of eligibility for benefits consistent with this disposition.

REVERSED and REMANDED.