Over the last years, increasing attention has been paid to Personal Learning Environments (PLEs) as an effective framework for lifelong learners, and to the need for a smooth integration of formal and informal learning. A wider and wider range of open source and free learning applications on the web are offering lifelong learners powerful tools to construct and characterise their own PLEs. Technologically speaking, this change of perspective manifests in a learning web where information is distributed across sites. However, knowledge management becomes an issue, and personalisation requires the support of semantics applied to social components. This work focuses on the characterisation of adult lifelong learners’ PLEs by implicit and explicit tools of personalisation. The synergy of formal and informal learning in the dynamic construction of a lifelong learner’s PLE has been explored. The SSW4LL (Social Semantic Web for Lifelong Learners) format has been devised, and the SSW4LL system, built on Moodle 2.0 integrated with an adaptive mechanism (conditional activities) and some tools of Social Semantic Web (Semantic MediaWiki, Diigo and Google+), has been designed, implemented and successfully validated as a device suitable to provide a dynamically personalised learning environment to the lifelong learner. Specifically, this volume thoroughly illustrates the implementation of the whole SSW4LL format in its validation course SSW4LL 2011, and discusses the results of a comprehensive literature review and the outcomes obtained from SSW4LL 2011. The integration of social software into formal learning environments can make a qualitative difference to giving adult lifelong learners a sense of ownership and control over their own learning and career planning, and can aid them to be effectively self-directed and self-regulated.