What effects will the implementation of the quality standard ISO 9000 have regarding working conditions and competitive advantages? Which are the most important change process characteristics for assuring improved working conditions and other desired effects? These are main questions behind this study of six furniture-making companies which implemented ISO 9000 during the period 1990-1993. The results show that customer requirement was the dominating goal to implement ISO 9000. Five of the six companies succeeded in gaining certification. The influence on working conditions was limited to better “order and method”, more positive attitude towards discussing quality shortcomings, a few workplace improvements, work enrichment caused by additional tasks within the quality system and a better understanding of external customer demands. The negative effects were new, apparently meaningless tasks for individual workers as well as more stress and more physically strenuous work. The effects on companies were a decrease in external quality-related costs and improved delivery precision. The study confirms the importance of the change process and identifies “improvement methodology” as the most important characteristic.