The objective of ESA’s Next Generation Gravity Mission is long-term monitoring of the temporal variations of Earth’s gravity at high time (3 days) and space (100 km) resolution. Such variations carry information about mass transport in the Earth system produced by the water cycle and the related mass exchange among atmosphere, oceans, cryosphere and land, and will complete our picture of Global Change with otherwise unavailable data. The basic datum is the distance variation between two satellites measured by a laser interferometer; as a necessary complement, accelerometers measure the non-gravitational accelerations, to be separated from the gravity signal in the data processing. The optimal satellite formation comprises two pairs of satellites, at 100 km mutual distance, on low (≈340 km) circular orbits with 89° and 70° inclination. The NGGM is a candidate Mission of Opportunity of ESA’s Earth Observation programme. Studies and technology development activities have advanced the maturity of the system concept and of the key subsystems (attitude and drag control, proportional thrusters, laser optics and electronics) for the mission to be proposed for adoption in 2022 and launch in the 2026-2028 time frame. The latest stand of the ESA studies is illustrated, concerning both the platform (featuring drag-free control, high-stability temperature control, drawing on the heritage of GOCE) and the laser interferometer instrument, for which two designs have been extensively studied, “Transponder” and “Retro-Reflector”, one of which will be selected for flight. A hybrid breadboard of the “off-axis” Retro-Reflector concept is being built and tested.