Ageism and age discrimination in the labour market have been topics of scholarly interest since the early twentieth century. Today, in markedly different economic conditions, with increasingly globalised labour markets, the victories and failures of workers' movements, and the changing conditions of the European welfare state, the problem of unequal and negative treatment of older workers still prevails. This chapter looks at the phenomenon of age discrimination and ageism in the labour market from a socio-political perspective and draws attention to deciding factors in its emergence. We add to the individualistic and micro accounts adopted by psychological research (see Lev et al. 2018; Chap. 4, in this volume) and the meso level studies of organisation and work environment conditions (see Naegele et al. 2018; Chap. 5, in this volume) by examining the role of macrostructural processes and transformations to identify their link to the persistence of ageism and age discrimination in contemporary labour markets. First, we provide an overview of the most common conceptual understandings of ageism and age discrimination in employment. Second, we investigate the dynamics between the phenomena of ageism and age discrimination and a range of socio-political contexts, cultural settings, and legal and economic conditions. We then discuss the costs and consequences of age discrimination in employment, and examine various policy responses to these costs and consequences.