A workshop for high maturity organizations was held on November 16-18, 1999, at the Software Engineering Institute (SEI) in Pittsburgh. The purpose of this workshop was to better understand practices that characterize Level 4 and 5 organizations. Topics of discussion included both practices described in the CMM (Capability Maturity Model) and other practices that have a significant impact in mature organizations. Two themes were anticipated to be important to the workshop participants: statistical process control for software and the reliability and credibility of Level 4 and 5 assessments. Additional topics were solicited from the participants on CMM integration, measurement, technology, human issues, and quality assurance. This report contains brief summaries of the high maturity organizations participating in the workshop and the various working group reports.