The First International Conference on Mobile Lightweight Systems (MOBILIGHT) was held in Athens during May 18-20, 2009. The decision to organize a scientific event on wireless communications, where competition is really enormous, was motivated by discussions with some colleagues about the current unprecedented request for lightweight, wireless communication devices with high usability and performance able to support added-value services in a highly mobile environment. Such devices follow the user everywhere he/she goes (at work, at home, while travelling, in a classroom, etc.), but also result in exciting - search, development and business opportunities. Such a scenario clearly demands significant upgrades to the existing communi- tion paradigm in terms of infrastructure, devices and services to support the anytime, anywhere, any device philosophy, introducing novel and fast-evolving requirements and expectations on research and development in the field of information and com- nication technologies. The core issue is to support the desire of wireless users to have 24/7 network availability and transparent access to "their own" services.