The aim of this meta-analysis was to examine the magnitude of the relationship between social influence and both PA behavior and PA-related social cognitions among samples of adults with physical disabilities, including those with chronic conditions that can lead to a physical disability. A comprehensive literature search was conducted to identify studies involving adults with physical disability, a measure of social influence, and a measure of PA behavior or PA-related social cognitions. A total of 27 studies with 4,768 participants yielded 47 effect sizes to be included for meta-analysis. Significant, small- to medium-sized relationships were identified between social influence and PA behavior, and social influence and PA-related social cognitions. These relationships suggest that social factors positively associate with physical-activity-related social cognitions and should be targeted when promoting physical activity behavior change among adults with a physical disability.