This book examines the determinants of immigration policy for workers in low-skilled jobs (LILSO) in democratic states. It moves beyond conventional economic explanations of migration policy and explores the complex interplay of political, historical, institutional, and social factors that shape labor immigration regulations. Key themes include:• The role of institutions and historical contexts in shaping long-term migration policy trends.• The political and social conditions that lead to policy changes beyond economic drivers.• The interaction between stable institutional frameworks and short-term political and societal shifts.Methodologically, it employs Fuzzy Set Qualitative Comparative Analysis (fsQCA), a case-oriented approach that allows for the identification of complex causal patterns and multiple pathways leading to similar policy outcomes. By studying nearly 30 democratic countries and over 80 immigration policy reforms between 1990 and 2019, the book presents a comparative analysis of migration regulation types and the policy shifts that occur under different economic and political conditions.