Abstract: The exclusion of people with disabilities from clinical research without appropriate justification is discriminatory, is counter to federal regulations and research guidelines, and limits study generalizability. This matter is understudied, and data on the disability status of trial participants are rarely collected or reported. We analyzed ninety-seven recent interventional protocols in four therapeutic areas registered on ClinicalTrials.gov. Eighty-five percent of protocols allowed broad investigator discretion to determine eligibility, whereas only 18 percent explicitly permitted people with disabilities to use forms of support (such as supported decision making or assistive devices) to facilitate study participation. Eligibility criteria affecting people with disabilities included exclusions for psychiatric (68 percent), substance use (62 percent), HIV or hepatitis (53 percent), cognitive or intellectual (42 percent), visual (34 percent), hearing (10 percent), mobility (9 percent), long-term care (6 percent), and speech and communication (3 percent) disability-related domains. Documented justification was provided for only 24 percent of these exclusions. We recommend greater scrutiny of study eligibility criteria, scientific or ethical justification of exclusions, and accessible study design.