Longitudinal studies are designed to be employed to describe and analyse societal changes over time. The overall purpose of Understanding Society is to provide high quality longitudinal data about subjects such as health, work, education, income, family, and social life to help understand the long term effects of social and economic change, as well as policy interventions designed to impact upon the general well-being of the UK population. This paper showcases the opportunities that Understanding Society opens up for rigorous longitudinal cohort analysis of various life course trajectories and is structured as follows. Section 2 describes data and methods. Section 3 presents findings on the sample sizes of birth cohorts in Understanding Society and is organised in three parts. Section 3.1 provides overview on the number of respondents in both adult and youth samples. Section 3.2 focuses on discussing younger cohorts born after 1990s who joined the Study as children (including in BHPS) and their transition to adult sample. Section 3.3 covers event histories collected retrospectively and provides examples of the cohort analysis of some of the first life course transitions (e.g. transition to first job and transition to first partnership). Additionally, Section 4 presents the review of research papers that use the Study for various cohort analyses.