The goal of this project is therefore to substantially advance the state-of-the-art in the direction of overcoming the above-mentioned issues by employing a team of Micro Aerial Vehicles (MAVs) as robotic platform, with a particular focus on quadrotor MAVs (a widespread and easily customizable mobile robotic platform with low cost, high agility and pervasiveness in 3D space). The project will address the design and implementation of fully decentralized and sensor-based group behaviors by only resorting to onboard sensing (mainly cameras and IMU) and local communication (e.g., bluetooth communication, wireless networks). Topics such as individual flight control, formation control robust against sensor limitations (e.g., limited field of view, occlusions), distributed estimation of relative positions/bearings from local sensing, maintenance of architectural properties of a multi-MAV formation will be touched by the project. As final demonstrator of the developed technology, the project will exploit the MAV group as a versatile and mobile localization system able to provide localization services to other robots in visibility of some of the MAVs (e.g., some ground robots). The MAVs will not be bound to keep a given specified formation, but they will freely arrange themselves in space according to any internal criterium, e.g., for enhancing the localization accuracy of the tracked ground robots, or for coping with their unavoidable sensory limitations (limited visibility, occlusions). This will effectively result in an autonomous flying mobile localization system ready to be deployed in indoor (and possibly outdoor) environments, freeing from the need of relying on complex external (Vicon-like) facilities or possibly unreliable services (GPS).