This special issue of the Future Generation Computer Systems (FGCS) journal is devoted to papers selected from the 6th International Conference on Ubiquitous Computing and Ambient Intelligence (UCAmI 2012) and the 4th International Workshop on Ambient Assisted Living (IWAAL 2012), held in Vitoria-Gasteiz, Spain, on 3-5 December 2012. On the one hand, UCAmI focuses on the ubiquitous computing and ambient intelligence research, which represent a new generation of user-centred computing solutions, aiming to find new ways to obtain a better integration of Information and Communication Technology (ICT) in everyday life devices and activities. On the other hand, IWAAL focuses on Ambient Assisted Living (AAL), an important application domain of ambient intelligence that aims to contribute with ICT research applied to enabling assistive living environments