Gyros Clocks Interferometers...: Testing Relativistic Graviy in Space Overview An Overview of Solar System Gravitational Physics: The Theory—Experiment Interface Determination of the Gravitational Constant The Lense—Thrirring Effect The Lense—Thirring Effect: From the Basic Notions to the Observed Effects Gravity Probe B: Countdown to Launch Gravitomagnetism and the Clock Effect Spinning Relativistic Particles in External Fields Detection of Gravitational Waves The GEO 600 Gravitational Wave Detector Status Research Development Gravitational Radiation Theory and Light Propagation Relic Gravitational Waves and Their Detection The Equivalence Principle Principles of Equivalence: Their Role in Gravitation Physics and Experiments That Test Them STEP: A Status Report High Sensitive DC SQUID Based Position Detectors for Application in Gravitational Experiments at the Drop Tower Bremen Space Accelerometers: Present Status Searching for Extra Dimensions and New String Inspired Forces in the Casimir Regime Relativistic Effects in the Motion of the Moon Lunar Laser Ranging — A Comprehensive Probe of the Post Newtonian Long Range Interaction Testing Relativistic Gravityand Measuring Solar System Parameters via Optical Space Missions Clocks and Rods Clocks for Length and Time Measurement SpaceTime Mission: Clock Test of Relativityat Four Solar Radii Pulsar Timing — Strong Gravity Clock Experiments Quantum Tests of General Relativity Relativistic Phase Shifts for Dirac Particles Interacting with Weak Gravitational Fields in Matter—Wave Interferometers Spin in Gravity Spin in Special and General Relativity Testing the Dirac Equation Electromagnetic Field and Gravity How Does the Electromagnetic Field Couple to Gravity in Particular to Metric Nonmetricity Torsion and Curvature. Many new tests of gravity and in particular of Einsteins general relativity theory will be carried out in the near future: The Lense Thirring effect and the equivalence principle will be tested in space; moreover gravitational waves will be detected and new atomic interferometers and clocks will be built for measurements in gravitational and inertial fields. New high precision devices have made these experiments feasible. They will contribute to a better understanding of gravitational physics. Both experimental developments and the theoretical concepts are collected in this volume. Exhaustive reviews give an overall insight into the subject of experimental gravitation.