Increased older women’s socioeconomic vulnerability (SEV) as a growing social problem across the globe, including Bangladesh, has garnered attention to explore the pathways of life course trajectories through which childhood socioeconomic disadvantage (CSD) generates subsequent disadvantages in life. Despite this growing interest, past research has poorly conceptualized and integrated the pathways of early life course transitions and subsequent disadvantages to explicate the complex relationship between CSD and SEV in older life. Drawing from the dynamic life course framework, in this chapter, we develop an integrated theoretical framework that helps understand critical pathways of girls’ early life course transitions (e.g., early marriage, family formation, and family role allocation) and subsequent disadvantages through which CSD generates SEV older life. Evidence from past life course research and sequential case study analysis of Bangladeshi older women suggests that older women born between 1960 and 1970 and grown in CSD led to early marriage, family formation, and family role allocation. These early life course transitions that occurred during adolescence generate socioeconomic disadvantages during early adulthood through adulthood. Along with these early life course transitions, further marital transitions to widowhood and subsequent changes in social networks accelerate their SEV in older life. Evidence in this chapter, however, contributes to the critical pathways of the early life course transitions and subsequent potential disadvantages through which girls’ CSD develops their SEV in older life. Social implications are discussed to prevent and reduce women’s SEV in later life.