This chapter begins by highlighting the rise of vulnerability as a term in social policy, and the three-level approach that is used to examine it. The first level is definitional, examining the possibility of defining vulnerability and vulnerabilities through a consideration of relevant literature and a number of recent policy documents. The second looks at how policy developments in Scotland and England have diverged, particularly since 2010, and how vulnerability has become more central to education policy in England. The third level focuses on practice, presenting research undertaken by the authors into a programme developed to support vulnerable children, young people, and families in Northern England as a case study exemplifying some of the factors affecting the effectiveness of programmes in which schools played an important but not central part. This practice perspective is still too often overlooked in discussions of policy and definition, and it is suggested that its inclusion will contribute to the ongoing debate about both how best to support vulnerable families and the implications for education and social justice.