There is a segment of the population, termed the underclass or socially excluded, who our current public policies do not reach. Despite universal and even targeted programming, youth who have experienced pervasive and often inter-generational exclusion still form the majority of those who find themselves at the end-of-the-line, in services areas such as social assistance and corrections. Although ethnographic studies have documented the life circumstances of specific marginalized groups, quantitative analyzes suggesting concrete policy and program directions are severely lacking. This book develops a life-course analysis of the interconnected webs of influence that push a minority of youth along entrenched trajectories of exclusion from school, extra-curricular activities, family and peers, while the majority progress toward inclusion. Even though no one person or group could be said to be completely responsible, we are all implicated in perpetuating or conversely combating the exclusionary practices that underlie our most severe social problems. Consequently, this book will be of interest to a broad range of readers including parents, teachers, policy makers and professionals.