The aim of this dissertation was to disclose and critically investigate the social meaning of the children's participation in family law proceedings. The research project was specifically delimited to the world of policy, to the world of professional social work, and first and foremost to the world of the child. Using an  applied  phenomenology,  following  Schiltz  sociologically  grounded phenomenology, the research design includes theoretical as well as qualitative studies. In relation to the world of the child, classical phenomenologists as well as contemporary, critical phenomenologists were guiding in the orientation towards research approach and analysis of the results. The doctoral dissertation is a compilation thesis that consist of four articles, in which three have been published in peer-review journals. The first article aimed at disclosing the meaning of children's participation within the world of professional social work in the situation of family law proceedings. The second article was a theoretical study into the sedimented meaning of children's participation within the world of policy. The third article focused on the possibility of listening to the social world of the child in relation to the conceptualization of children's participation. The fourth article was a qualitative study in which children and young adults' experiences of living through family law proceedings were investigated. The four studies show that the adult conceptualization of children's participation is not properly grounded in how participation as a social phenomenon is experienced within the world of the child. For instance, in relation to family law proceedings, the necessity of assessing children's age and maturity as a sedimented prerequisite to participation is at odds within the world of the child as they are already taking part of and acting on relational matters within the family. The findings suggests that an attunement to the social world of the child as well as acknowledging children's lived participation is important if children's formal rights to participate as well as being protected are to be taken seriously.