The Cassini/Huygens spacecraft flew by Venus on June 24, 1999, and the Earth on August 18, 1999. These two events provided the Cassini Project with its first opportunities to design coordinated scientific observations at planetary encounters. In addition to exercising capabilities of the science instruments as well as the spacecraft and performing instrument calibrations, new scientific data were obtained. We present an overview of these two planetary flybys, describe the processes used to plan and design the observations, and highlight the major scientific results presented in the papers that follow. ¿ 2001 American Geophysical Union