Evaluations of participative ergonomics (PE) interventions have reported mixed results, potentially due to both program and theory deficits. In a multiple case study of four worksites in different companies using a quasi-experimental approach, we examined process, implementation, and effects. The process evaluation was based upon fieldwork and interviews with approximately 90 persons. Implemented changes were documented by PE teams and intensity judged by the research team. The effect evaluation was performed using questionnaire-based measures (physical effort, influence, pain and potential confounders) among cohorts present both before and after the changes (N=258). Ergonomic change teams (ECTs) faced challenges securing employees' time, varying management commitment and significant production pressures. Nevertheless they actively introduced between 10 and 21 changes over 10-20 months of activity. Limited intensity of exposure reduction was observed, resulting in no discernible effects on physical effort or pain among the employees. Potential reasons that may account for limited effects and lessons for workplace parties, practitioners, and intervention researchers are discussed.