Social network research is well-equipped to help life course scholars produce a deeper and more nuanced approach to the principle of "linked lives," one of the cornerstones of the field. In this issue on Networked Lives, nine original articles and two commentaries generate new theories, empirical findings and methodological applications at the intersection of the fields of social networks and life course research. In this introduction, we reflect on these advances, highlighting key findings and challenges that await scholars in building more robust synergy between the two fields. Social networks emerge as key structural forces in life courses, yet there is much to learn about the mechanisms through which their effects on people's lives come about. There is a need to study further how networks evolve through the rhythm of life events, and to analyze broader and more complex networks that capture the roles and influences of relations beyond intimate or family ties. These papers demonstrate that there is much to be gained in probing how individuals are linked to and unlinked from others over time, and in carrying conceptual and methodological advances across social network and life course studies.