Individuals living with chronic physical or mental health/cognitive conditions must make decisions that are sometimes difficult about whether to disclose health information at work. This research investigated workers' decisions to not to disclose any information at work, disclosure to a supervisor only, co-workers only, or to both a supervisor and co-workers. It also examined personal, health, and work factors associated with disclosure to different groups compared to not disclosing information. Employed workers with a physical or mental health/cognitive condition were recruited for a cross-sectional survey from a national panel of Canadians. Respondents were asked about disclosure decisions, demographics, health, working experience, work context, and work perceptions. Multinomial logistic regressions examined predictors of disclosure. There were 882 respondents (57.9% women). Most had disclosed to both co-workers and supervisors (44.2%) with 23.6% disclosing to co-workers only and 7% to a supervisor only. Age, health variability, and number of accommodations used were significant predictors of disclosure for all groups. Job disruptions were associated with disclosure to supervisors only and pain and comfort sharing were associated with co-worker disclosure. The findings highlight that disclosure to co-workers is common despite being an overlooked group in workplace disclosure research. Although many similar factors predicted disclosure to different groups, further research on workplace environments and culture would be useful in efforts to enhance workplace support.