An asylum applicant challenged the Board of Immigration Appeals’ determination that the harms reflected in the undisputed record did not amount to persecution. The Supreme Court held that a reviewing court applies the deferential substantial-evidence standard to the agency’s persecution determination. Although the governing legal definition is reviewed independently, applying that standard to the historical facts is the kind of agency judgment Congress directed courts to uphold unless the evidence compels a contrary conclusion. Because the record did not compel a finding of persecution, the judgment was affirmed.