The aim of this randomized, controlled intervention study among operators in the aluminum industry in Norway was to examine the effects of a 1-year training program on musculoskeletal symptoms, psychosocial factors and coping. The program consisted of 10 meetings and focused on awareness of preventing musculoskeletal symptoms and on the process of promoting musculoskeletal health in the work environment. Three types of intervention groups comprised 549 workers from eight plants: (1) shift group with supervisor; (2) shift group without supervisor; and (3) managers only. A total of 721 workers were in a control group from the production line and 3699 workers in a control group from other sections. The number of operators included in the final evaluation was 2181. The effects were measured using a questionnaire including items on musculoskeletal symptoms, coping, job demands, control and social support. Participants in the intervention group, “operators without a supervisor”, used coping strategies more often and tended towards increased social support. We found no significant changes in musculoskeletal symptoms. The intervention groups implemented changes in the work environment such as redesigning the workplace, changing working tools and increasing job variation. We suggest that there will be further improvements when the changes implemented by the intervention groups have been in place longer.Relevance to industryIndustry uses various programs to reduce musculoskeletal disorders. However, their effects on health are little known. This study shows that training and actively involving the workers in solving specific problems in the work environment influence coping with musculoskeletal symptoms. This is important for preventing occupational disability from musculoskeletal disorders.