What From a very young age, children are part of multiple activities and relations within and across everyday life contexts (e.g. family, daycare). In the monograph I employ a relational research strategy by observing children (age 1-5) in these everyday life contexts to catch children's perspectives and to explore children's agency in and across social situations. Hence, the aim is twofold: to 1) develop ground-breaking theoretical understandings of children's agency and subjectivity in relation to daily transitions within and across everyday life contexts, and 2) to problematize that concerns for children's developmental conditions are often being assessed without considering children's concrete everyday life conditions or including their perspectives. Why The monograph contributes with ground-breaking knowledge on children's development and well-being. In psychology, marginalization have been studied as a results of risk factors. Hence, problems in children's lives are often being assessed by associating isolated variables such as child behavior and parental resources/deficits to a prospective outcome. It is crucial to develop new ways of thinking about children in marginalized positions since the complexity of everyday living comprise children's developmental conditions. The monograph contributes with a focus on children's agentic ways of participating in and moving between everyday life contexts. This focus enables analysis of the situated meanings of marginalization and why children relate differently to adversities. How I draw on empirical data from long-term participant observations of 5 children (1-5) in their everyday life contexts. By taking a point of departure in cultural-historical research traditions I am able to emphasize how children are active subjects in their own lives. This theoretical framework is fruitful for gaining a comprehensive approach to the study of children. Hence, taking a point of departure in cultural-historical traditions allows for developing novel understandings of how social problems, adversity and conflicts in children's lives are interconnected with their participation in a compound everyday life across contexts and within a multiplicity of social relations (e.g. other children in day care settings, parents, caregivers, siblings). SSR The monograph aims to develop theoretical knowledge also relevant for professional practice. For instance, in child protection services professionals are obliged to take children's perspectives into consideration in the handling of children's cases. However, including preverbal children's perspectives often are considered a challenge in professional work. The monograph offers novel understandings of young children in marginalized positions by focusing on their ways of participating in and across everyday life contexts. I show how it is possible to approach children's perspectives precisely by focusing on their activities in daily living. In this way, the monograph contributes with knowledge relevant for qualifying the professional work with young, preverbal and marginalized children by 1) offering ways to include these children's perspectives, 2) providing a more complex framework for understanding the situated meanings and consequences of marginalization. In this way, the knowledge produced enables processes of inclusion of marginalized groups and often neglected voices in society.