This article reports on the course and the findings of a two year longitudinal study aimed at investigating the impact of a knowledge management project on an organization's communication and decision structures. The knowledge management project introduced cross-functional Communities of Practice into a division of a large automotive company. The author-researcher applied a multi-perspective and multi-method research approach called "balanced evaluation" for being able to unravel changes in organizational knowledge and decision patterns. This system-theoretic approach to evaluation of transformation processes is described and compared to more traditional approaches; findings are presented and discussed. URN: urn:nbn:de:0114-fqs1003108