This thesis provides a comprehensive analysis of migration’s diverse impacts across low-income (16 African countries), upper-middle-income (T¨urkiye), and high-income (the United Kingdom) settings, focusing on health, political dynamics, and labor market outcomes. Recognizing the inherent endogeneity and reverse causality in migration studies, this research employs a range of econometric techniques, including instrumental variable (IV) methods and two-way fixed effect models, to establish causal relationships. Chapter 2 investigates the political consequences of refugee presence in 16 Sub-Saharan African countries, leveraging UNHCR refugee data and Constituency-Level Elections Archive (CLEA) data, and finds that inclusive refugee policies enhance incumbent support and reduce electoral competition by improving access to public services and stimulating local economies, as evidenced by Afrobarometer survey data. Chapter 3 examines the health implications of the Syrian refugee influx on Turkish children under five, utilizing the Turkish Demographic and Health Survey (TDHS) and an IV approach to address endogenous refugee settlement. Findings reveal a positive impact on children’s anthropometric measures, driven by increased maternal time, particularly among low-educated mothers. Chapter 4 explores the pay-health nexus in the UK, using the Understanding Society Survey (USS) and a Two-Stage Least Squares (2SLS) approach to demonstrate that high pay significantly improves physical and mental health. This chapter also examines the heterogeneous effects of gig work and multiple job holding on health, using quantile regression, and analyzes the generational differences in health outcomes among migrant populations. The thesis highlights the importance of inclusive migration policies and strategic aid distribution in maximizing positive spillovers for host communities, while also addressing health inequalities through improved pay and job conditions. It underscores the need for context-specific policies that facilitate migrant integration and ensure equitable outcomes, contributing to a deeper understanding of migration’s complex socioeconomic impacts.