The Terrestrial Planet Finder (TPF) will detect and characterize Earth-like planets around nearby stars. NASA is currently funding a number of small studies to look at trade-offs in the design of TPF. The possible trade-offs include orbit location (1 to 5 AU), aperture size (4 to 2 m), and physically connected baselines vs. separated spacecraft flying in close formation. The performance of TPF depends critically on the brightness of the local zodiacal dust cloud at the observing site, and on the brightness and degree of structure in the zodiacal dust cloud around other stars. Sensitivity calculations indicate that TPF could accomplish its goals using 4-5 m telescopes operating at 1 AU. Such a mission would have many advantages relative to a mission operating smaller telescopes in lower background conditions at 5 AU.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.