The extraordinary challenges faced in planning the first human expeditions to the surface of another solar system body led to the development of a new and distinctive approach to exploration in general and scientific field work in particular. Those involved had to deal effectively with the extreme limitation in access to and resources available for a target as remote as the lunar surface, while developing a truly rigorous and effective approach to science activities ranging from collecting samples to deploying field instruments. As the results ranging from the truly representative lunar sample collection to the first measurements of the lunar environment indicate, the ground-breaking approach developed in response to these challenges was successful. The principal characteristics and keys to success of this approach, how these affected the planetary exploration that followed, and implications for future exploration, will be discussed in this book. One of the most useful online sources is the Apollo Surface Journal, which I used extensively to perform the analyses of Apollo surface activities described in the book. A broad cross-section of those who played important roles in the Apollo program have had oral history interviews. I will quote from four who played critical, different, and complementary roles in the development of the Apollo surface exploration program, including Farouk El Baz, Harrison Schmitt, Lee Silver, and Jim Head.