Summary The percentage of older workers aged 45 years and over in Quebec’s labour market is constantly growing. In the education sector, a substantial proportion of the workforce is aged 45 years and over (41%), and a third of all staff members left their jobs between 2009 and 2018 (Grenier, 2009). Recent statistics also show that both physical and psychological injuries to workers in Quebec’s education sector are often associated with time off work compensated by the Commission des normes, de l’équité, de la santé et de la sécurité du travail (CNESST). These injuries are more likely to affect older workers in a range of positions (e.g., teachers, administrative staff) (Busque, 2012). The general goal of this study is to identify the determinants for keeping employees aged 45 years and over of a Quebec school board (SB) at the workplace and in good health. Based on a mixed-methods design with a quantitative phase (Phase 1) and a qualitative phase (Phase 2), the study was carried out among older workers at an SB. During Phase 1, statistical analyses were done on longitudinal data of various types: (a) self-report data collected during an intervention offered to the staff at the SB during the period from 2004 to 2012 (e.g., psychosocial factors and aspects of psychological health); (b) data certified by the employer for the period from 2002 to 2015 (e.g., position, years of service, absences, retirement). During la Phase 2, 28 semi-structured interviews were carried out with workers employed at the SB since 2004 or earlier who were aged 45 years and over. The interviews’ contents were then analyzed. This study provides a better understanding of how working conditions characterized by the presence of psychosocial factors foster older workers’ psychological health and encourage them to continue working at the SB rather than to decide to take early retirement. The results of Phase 1 highlighted the fact that workers at the end of their career show higher levels of workplace stressors and demotivation than workers in mid-career. For retired workers, autonomy and flexible schedules contributed to their satisfaction at work and their introjected motivation. These positive aspects of psychological health at work, in turn, determined their choice to keep working at the SB until their normal retirement date. Compared to the group that opted for early retirement with financial penalties, the workers who chose normal retirement are characterized by higher levels of job satisfaction and satisfaction with the institution. The results of statistical analyses carried out on the certified data show that absence due to physical disability affects more participants in mid-career than at the end of their career. On the other hand, absence due to psychological disability affects more participants at the end of their career and workers who have opted for early retirement. Absence due to psychological disability affects fewer participants but its duration exceeds that for physical disability in average days per year. Finally, the results on attendance rates at work corroborate the absenteeism results for workers who are still employed at the SB: workers in mid-career are less likely to be absent for reasons of psychological disability, while participants at the end of their career are absent less often for reasons of physical disability. The results of Phase 2 supported and complemented the information obtained in Phase 1 regarding the psychosocial factors and psychological health aspects that impacted the retention of the older workers included in this study. The respondents mentioned certain unfavourable factors, such as workplace stressors and overwork. Fatigue and dissatisfaction resulting from a period of change and budget cuts are balanced by favourable factors, such as social support from colleagues, superiors and the SB, and the possibility of adjusting workload, duties and work schedules. These factors, which play an important role in the intent to continue working at the SB, are supplemented by human resources management practices designed to retain aging workers, such as gradual retirement, possibilities for promotion and training, and by the financial position of workers and their families (e.g., income), the health of the worker or the worker’s spouse, and other factors related to life outside the workplace (e.g., family care, non-work activities). This was the first study conducted in Quebec that shows that keeping workers on the job and healthy is affected by different kinds of factors. Workers start considering these factors in mid-career because they need to take account of their needs (e.g., values, career trajectory) through different systems and plans (e.g., organization, health care, insurance, retirement), while keeping other stakeholders in mind (e.g., clients, colleagues, family). Older workers can be retained by means of interventions that target optimal working conditions by balancing demand with available resources, meeting both the needs of the aging workforce and the organization’s need for productivity.