Geodetic measurements provide high-accuracy observations of the deformation of the Earth on time-scales ranging from a few hours to decades; they constitute an integral part of every study of the planet's dynamic behavior. This book describes geodetic methods and results that are relevant to the study of the Earth, along with the geophysical and geological implications of these observations. The measurement techniques include classical terrestrial observations in use since the late nineteenth century as well as modern methods based on space technology, interferometric observations of radio stars, the tracking of satellites, and laser-ranging to the Moon. Because a complete interpretation of the geodetic observations requires a discussion of Earth physics, geological processes, and meteorological and oceanographic phenomena, this book will be of interest to all geophysicists.