Summary Approximately one person in three worldwide appears to live with a persistent musculoskeletal disorder (MSD). A number of authors point out the significant influence of psychosocial factors, including anxiety, on the development of long-term disability. Excessive worries, which are associated with anxiety, have been documented in workers with persistent musculoskeletal pain. Such worries do not promote adaptation in problematic situations. To date, no study has attempted to understand these worries in relation to the work environment. Yet a better understanding of this phenomenon appears essential if we are to offer more effectively targeted actions for workers with long-term work disabilities. From a broader perspective of facilitating a prompt and sustainable return to work, the general objective of this study was to develop courses of action for work rehabilitation interventions by studying worries as a source of information for determining the pertinent factors to consider during the return to work (RTW). Two specific objectives were pursued to this end: (1) to examine workers’ worries in greater depth and in relation to the work environment, as well as the intensity of these worries and their interference in the RTW process, and (2) to develop courses of action to guide work rehabilitation interventions for workers with MSDs. An exploratory study with a mixed-methods design was conducted, using a pragmatic approach (Creswell, 2003). An observational and prospective repeated-measures design, with questionnaires self-administered by workers with a long-term disability resulting from an MSD, was used for objective 1. Qualitative data were also collected to acquire a deeper understanding of the phenomenon under study. Participant inclusion criteria were (1) having an MSD that resulted in a sick leave of more than three months from a regular job and receiving compensation from Québec’s workers’ compensation board (the Commission des normes, de l’équité, de la santé et de la sécurité du travail, or CNESST); (2) aged 18 to 64 years; (3) able to speak French or English; and (4) having a therapeutic return to work (TRTW) included in the treatment plan, or RTW included as an objective of the rehabilitation program. Exclusion criteria were (1) having an MSD related to a specific pathology (e.g. recent fracture, metabolic disease, inflammatory or infectious neoplasia of the spinal column) and (2) the presence of a severe mental disorder (e.g. personality disorder in Cluster A of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (American Psychiatric Association, 2000), i.e. paranoid, schizoid or schizotypal personality disorder or a past or present psychotic episode) in their medical record. For objective 2, a survey of work rehabilitation clinicians shed more light on their perception of the clarity, pertinence, exhaustiveness and feasibility of the courses of action derived from the results of objective 1. These clinicians had to have more than two years of work experience in an organization offering a work rehabilitation program to clients compensated for a work-related MSD. For objective 1, a total of 80 workers agreed to participate in the study. Fifty-six of them completed the last measure at the end of their work rehabilitation program, for the main factors under study. The final predictive model of non-RTW at the end of the work rehabilitation program was highly significant. It explained 54% of the variance in non-RTW (Pseudo R2 = 0.54; p <.0001). The two main factors significantly associated with non-RTW at the end of case management were the margin of manoeuver at work (MMW) and the presence of worker-reported intense worries. When MMW was absent during follow-up, the workers were 8.52 times less likely to return to work. When intense worries were present, the workers were twice as likely not to return to work. The other factors also associated with non-RTW were intolerance of uncertainty, the perception that it was useful to worry, and lastly, the intensity of the generalized anxiety. Subsequent analyses revealed that a lack of MMW was associated with the workers’ worries about their disability episode or RTW. In fact, they considered that their worry stemmed from a situation currently related to work and saw themselves as experiencing a high level of uncertainty in this regard. The screening interviews conducted for psychological disorders at the time of the first measure revealed that 71% of the workers experienced psychological difficulties at clinical or sub-clinical levels. The majority of these participants reported difficulties related mainly to their disability episode. Regarding objective 2 and based on the results obtained in the previous objective, six courses of action were developed for the practice of work rehabilitation. They concerned among other things, the need to evaluate workers’ worries and to promote a margin of manoeuver at work. These courses of action were submitted to 10 clinicians. Overall, the clinicians indicated acceptable levels of agreement with their clarity, pertinence and feasibility. While the feasibility results were lower, they were still acceptable. This was particularly true for three courses of action with levels of agreement lower than 3 out of 4. Regarding exhaustiveness, a few clinicians made comments or suggestions. Essentially, they highlighted the need to operationalize certain courses of action that they saw as difficult to define with precision. They also suggested including other actors, such as employers or insurers, to factor in the legal constraints inherent in certain actions, and raised the need for training. Very few studies have examined workers’ psychological difficulties in light of their long-term work disability resulting from an MSD. This study provides a more nuanced understanding of the worries experienced by such workers. One of its major contributions is that it highlighted the fact that the worker-reported worries were current and work-related. These observations were also corroborated by the participating occupational therapists, who identified the same issues, as well as low MMW. Several courses of action were formulated, and on an exploratory basis, were deemed pertinent, clear and acceptable.