For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit: www.BMSStudyConnect.com Inclusion Criteria: - Moderately to severely active Ulcerative Colitis (UC) diagnosed prior to the Screening Visit - Evidence of UC extending beyond the rectum, as determined by baseline endoscopy - Has had an inadequate response, loss of response to, or is intolerant to at least 1 of the following treatments for UC: oral aminosalicylates, systemic corticosteroids, immunomodulators, biologic therapy Exclusion Criteria: - Diagnosis of Crohn's disease or indeterminate colitis - Has documentation of positive test for toxin producing Clostridium difficile, or polymerase chain reaction examination of the stool - Apheresis within 2 weeks of randomization - History of or currently active primary or secondary immunodeficiency, or participants with known genetic disorders as a cause for colitis Other protocol-defined inclusion/exclusion criteria apply