The life course approach, also known as the life course perspective or life course theory, refers to an approach developed in the 1960s for analyzing people's lives within structural, social, and cultural contexts. The origins of this approach can be traced back to pioneering studies of the 1920s such as William I. Thomas and Florian Znaniecki's The Polish Peasant in Europe and America and Karl Mannheim's essay on the "Problem of Generations". Overview The life course approach examines an individual's life history and investigates, for example, how early events influenced future decisions and events such as marriage and divorce, engagement in crime, or disease incidence. The primary factor promoting standardization of the life course was improvement in mortality rates brought about by the management of contagious and infectious diseases such as smallpox. A life course is defined as "a sequence of socially defined events and roles that the individual enacts over time". In particular, the approach focuses on the connection between individuals and the historical and socioeconomic context in which these individuals lived. The method encompasses observations including history, sociology, demography, developmental psychology, biology, public health and economics. So far, empirical research from a life course perspective has not resulted in the development of a formal theory. Life course theory, more commonly termed the life course perspective, refers to a multidisciplinary paradigm for the study of people's lives, structural contexts, and social change. This approach encompasses ideas and observations from an array of disciplines, notably history, sociology, demography, developmental psychology, biology, and economics. In particular, it directs attention to the powerful connection between individual lives and the historical and socioeconomic context in which these lives unfold. Glen Elder theorized the life course as based on five key principles: life-span development, human agency, historical time and geographic place, timing of decisions, and linked lives. As a concept, a life course is defined as "a sequence of socially defined events and roles that the individual enacts over time" (Giele and Elder 1998, p. 22). These events and roles do not necessarily proceed in a given sequence, but rather constitute the sum total of the person's actual experience. Thus the concept of life course implies age-differentiated social phenomena distinct from uniform life-cycle stages and the life span. Life span refers to duration of life and characteristics that are closely related to age but that vary little across time and place. In contrast, the