In 2010, janitors and cleaners in the US suffered over 46,000 workplace injuries and had the 16th highest injury rate for all occupations (Seixas 2013). Muscle fatigue and discomfort are risk factors for work-related musculoskeletal disorders (MSDs)and can predict future pain and injury (Hamberg-van Reenen 2008). This study of UW custodial workers used pre- and post-modification surveys to assess discomfort for 16 custodial tasks surrounding the implementation of a participatory ergonomics program. The participatory ergonomics program brought together custodians, managers and health and safety personnel to develop task modifications using new tools and ergonomic training for some of the tasks. Analysis of the survey data used ordinal logistic regression with robust standard errors clustered by the individual to analyze discomfort models. Total reports of high severity discomfort decreased for most tasks, including all four modified tasks, after the ergonomic modifications were recommended. Attendance of trainings was associated with a reduction in multiple task discomfort but not with overall discomfort severity. Therefore, participatory ergonomics efforts between custodians, managers, and health and safety professionals may help reduce the burden of MSDs in this high-risk occupation.