LISA Pathfinder, formerly known as SMART-2, is the second of the European Space Agency's Small Missions for Advance Research and Technology, and is designed to pave the way for the joint ESA/NASA Laser Interferometer Space Antenna (LISA) mission, by testing the core assumption of gravitational wave detection and general relativity: that free particles follow geodesics. The new technologies to be demonstrated in a space environment include: inertial sensors, high precision laser interferometry to free floating mirrors, and micro-Newton proportional thrusters. LISA Pathfinder will be launched on a dedicated launch vehicle in late 2011 into a low Earth orbit. By a transfer trajectory, the sciencecraft will enter its final orbit around the first Sun-Earth Lagrange point. First science results are expected approximately 3 months thereafter.Here, we give an overview of the mission including the technologies being demonstrated.Keywords LISA Pathfinder · Gravitational waves · Inertial sensing · Laser metrology · Charge management · Micro-Newton thrusters · FEEPS · Colloids · DFACS PACS 04.80.Nn · 95.30.Sf · 95.55.Ym