I present a personal recollection of the history of system dynamics and observations about its present state. The article treats the history in two parts: first, my personal background and how all the threads came together to initiate the field of system dynamics; and second, the historical development of the cornerstone projects that shaped the field. These early works include industrial dynamics, urban dynamics, world dynamics, and the national economic model. The paper continues with an assessment of the present condition of the field. A companion paper (System Dynamics—The Next Fifty Years, also in this issue of System Dynamics Review), highlights challenges for the future. Copyright © 2007 Jay W. Forrester.