BackgroundReturning to work following a job-related injury or illness can be a complex process, influenced by a range of interrelated personal, psychosocial, and organizational components. System dynamics modelling (SDM) takes a sociotechnical systems perspective to view return-to-work (RTW) as a system made up of multiple feedback relationships between influential components.Design and MethodsTo build the RTW SDM, a mixed-method approach will be used. The first stage, that has already been completed, involved creating a baseline model using key informant interviews. Second, in two manufacturing companies, stakeholder-based models will be developed through interviews and focus groups with senior management, frontline workers, and frontline supervisors. Participants will be asked about the RTW process in general and more targeted questions regarding influential components. Participants will also be led through a reference mode exercise where they will be asked to estimate the direction, shape and magnitude of relationships between influential components. Data will be entered into the software program Vensim that provides a platform for visualizing system-structure and simulating the effects of adapting components. Finally, preliminary model validity testing will be conducted to provide insights on model generalizability and sensitivity.Expected Impact of the study for Public HealthThe proposed methodology will create a SDM of the RTW process using feedback relationships of influential components. It will also provide an important simulation tool to understand system behaviour that underlies complex RTW cases, and examine anticipated and unanticipated consequences of disability management policies.Significance for public healthWhile the incidence of occupational injuries and illnesses has declined over the past two decades, the proportion resulting in sickness absence has actually increased. Implementing strategies to address sickness absences and promote return-to-work (RTW) can significantly benefit physical and mental health, and work outcomes like worker engagement, job satisfaction and job strain. As a key social determinant of health, participation in paid work can also ensure that work-disabled individuals generate income necessary for access to housing, education, food, and social services that also benefit health. Improving RTW outcomes can also have significant societal benefits such as a reduction in workers compensation costs, increased economic activity and less burden on social assistance programs. Despite its benefits, returning to work after injury or illness is not a straightforward process and can be complicated by the individual, psychosocial, organizational and regulatory components that influence a disabled person’s ability to resume work activities.