Introduction: Baggage handling is considered to be a heavy manual handling job including biomechanical exposures suspected of increasing the risk for musculoskeletal disorders. Aims: To document low back pain (LBP), shoulder pain (SP), and physical and psychosocial factors in baggage handlers, and to evaluate the implementation of an ergonomic intervention aiming to increase the use of loading assist devices. Methods: A questionnaire was utilized to characterize pain and psychosocial work conditions in 525 baggage handlers. The postures of 55 baggage handlers during 114 shifts were measured using inclinometry, half shift video-recordings were made for subsequent task analysis, and the number of aircraft handled was registered. Associations for psychosocial and biomechanical exposures with pain were assessed using regression analyses. An ergonomic intervention was implemented and evaluated using questionnaires and repeated interviews. Feasibility, intermediate outcomes, barriers and facilitators were assessed. Results: The prevalence rates of reported LBP and SP were 70% and 60%, respectively. Pain interfering with work (LBP - 30% and SP - 18%) and high pain intensity (LBP - 34% and SP - 28%) were associated with poor psychosocial working conditions. Extreme postures with arms elevated >60° occurred for 6.4% of the total time, and in trunk flexion >60° for 2.1% total time. In contrast, 71% of the total time was spent in a neutral trunk posture. The 90^th percentile trunk forward flexion was 34.1°.  Daily shoulder pain increased in approximately one-third of all shifts and was positively associated with extreme work posture and the number of aircraft handled; this association was modified by influence and support. The intervention was delivered as planned, and dose received and satisfaction were rated as high. Motivated trainees facilitated implementation while lack of manager support, opportunities to observe and practice behaviors, follow-up activities, staff reduction, and job insecurity were barriers. Conclusion: The high prevalence rates of LBP and SP in baggage handlers were associated with psychosocial exposures, and daily shoulder pain was associated with higher biomechanical exposure. Barriers to implementation can be minimized by recruiting motivated trainees, securing strong organizational support, and carrying out follow-up activities.