Summary This study is part of the work published in Québec since the 1990s that has contributed to the emergence of a new field of research on paid work and students. This research is mainly focused on the impact of paid work on studies. However, only a few studies have addressed the potential health impacts related to students' paid work, in particular occupational accidents, musculoskeletal disorders (MDSs), psychological distress and fatigue.While student workers are at lower risk of occupational injuries than young dropouts, the increase in the school-work combination in the last 20 years led us to focus on this reality. In fact, compared with their counterparts in nine countries of the Organization for Economic Co-operation and Development (OECD), young Canadians rank first in the average number of weekly hours devoted to paid work and unpaid activities during the school week (Marshall, 2007). To better identify the occupational health and safety (OHS) issues related to this growing phenomenon, the present project aims to determine the effects of the combined activities and combined work constraints on the OHS of students who work during their studies, by taking into account the fact that they are also a group at risk of excessive drowsiness.A total of 94 young people from 19 to 21 years of age combining studies and employment were recruited using an existing longitudinal survey on educational pathways, lifestyles, and OHS. A first semi-structured interview, conducted at the start of the school session, established the profile of these young people's activities, the characteristics of their paid work, and the work constraints to which they were exposed. They then completed a log and wore an actigraph for 14 consecutive days to quantify their combined activities and to document their sleep habits. Validated questionnaires were also completed to evaluate the presence and severity of various OHS symptoms (MSDs, psychological distress, fatigue, sleep problems, etc.). At the end of the school session, a second semi-structured interview documented the changes that may have occurred in the profile of the activities and in the work constraints during the school session, documenting the strategies used by the young people to adapt to the said constraints and clarifying the relationship between work characteristics and OHS symptoms.Not surprisingly, the majority of the jobs held by the students were in the activity sectors traditionally occupied by young workers, such as retail sales, the accommodation industry, and the food service industry. However, our study shows that at the age of 19, some participants began to occupy technical level jobs related to their field of study, jobs that usually require more qualifications; this was most often the case for girls with jobs in health care or in education. Our study also shows that the profile of the activities characterizing the studies-work combination was not stable over time, but fluctuated significantly, particularly regarding their job. In general, students with one or more jobs did not try to lighten their school requirements by reducing, for example, their weekly number of course hours. The hours dedicated to paid work simply added to the course hours, school work hours, and study hours. On this point, the situation seems of more concern for college students and for those completing a high school vocational diploma or registered in general adult education.This study also shows that students with a job during their studies have to deal with a complete range of health risks, and that the characteristics of the job, the work schedules, and the employment paths have an impact on different health indicators. More precisely, two girls out of five and about one boy in five reported a general level of fatigue considered as requiring a medical consultation. More specifically, the analyses identified the combined work organization constraints, in addition to the psychological demand, social support at work, and the fact of having held a greater number of jobs since age 15 as factors associated with the severity of the chronic work-related fatigue. While the majority of these student workers did not consider their workload as too heavy, one participant in five nevertheless perceived his paid work as being difficult, tiring, demanding and stressful. Our results also show that approximately half of the student workers had sleep problems.In a survey carried out on this same population of student workers when they were 17–18 years of age (Ledoux et al., 2008), we noted that more than half of those who reported having felt pain in the year preceding the survey had also felt it in the last seven days. Once again, it seems that the students who have a paid job during their studies are a population dealing with a certain persistence or chronicity in the perceived musculoskeletal pain since almost all (91.3%) of those who had felt pain in at least one location of the body in the last 12 months preceding the current study also felt it during the week preceding the study. Once again, the girls stood out from the boys in the average number of pain sites reported. Our results also suggest a link between the number of physical constraints to which the student workers are exposed in the context of their job(s) and the presence of pain caused by the paid work. Also, the young people who feel job-related pain are generally exposed to a higher psychological demand.Finally, our study shows that young people often report uneasiness, discomfort and injuries following an accidental event. In many cases, these short-term effects do not translate into absences from work because part-time work (PTW) is such that the period between two work days is often long enough to recover from these consequences. Thus, one can conceive here the limit of the indicator that assesses the severity of an occupational injury from the absence duration when it involves PTW. As well, our results suggest that the occurrence of an initial occupational accident at the very beginning of the professional path, often in adolescence, increases the risk of suffering another later. Finally, this report ends with the presentation of a few intervention and research scenarios.