The planning for ambitious manned space missions has renewed interest in nuclear propulsion. During the late 1950s and into the 1970s substantial effort was devoted to nuclear propulsion, primarily a solid core thermal rocket engine. The program drew on the diverse nuclear and space related capabilities needed to successfully meet its development goals. Future development of nuclear propulsion systems can build on the technology and experience of those past efforts. This paper reviews the program history and suggests some lessons learned in terms of development approach and management that might contribute to a successful outcome.