We developed the framework presented in this book from two sources:
A long-range, three-phase research project that began in the early 1970s
Three decades of direct experience coaching, teaching, training, and consulting to leaders in organizations based in the United States, Canada, and Europe
This Appendix is divided into two parts. The first summarizes our three-phase research effort and cites the primary influences on our thinking about stages of leadership development. The second part describes the research methods we used in the intensive third phase. It also explains the reasoning behind our estimates of the percentage of managers at each level of leadership agility.