Between 2017 and 2018, the canton of Geneva implemented an unprecedented pilot policy in Switzerland: a scaling up of the regularization of undocumented migrants who met pre-established criteria. How has this transition impacted their living conditions and life aspirations? This book presents the results of a prospective study called “Parchemins”, conducted over five years among a number of the individuals concerned. Thanks to the rich dataset collected, this study shows how accessing a legal status influences the life course of these people, be it in terms of housing conditions, financial situation, social integration, health, or quality of life. It provides keys for interpreting these unique results, and presents recommendations for action aimed at both policy-makers and associations, with the goal of best accompanying these new citizens.