Art. 12 to 17 and art. 31 UNCRC are considered to refer to “participation rights”. These rights are considered the most “revolutionary” under the provisions of the UNCRC because they challenge traditional and tokenistic conceptions of childhood. The challenge however also lies in the balance to be found, in all settings, between structural adaptations necessary to favour child participation and the evolving capacities of the children themselves, who can only progressively exert their own rights directly. Another aspect is participation of children as individuals or as groups, notably their collective decision-making capacity. It looks like practice has outstripped theory. The difference between the child as a subject of rights and the child’s real agency as a social actor needs more theoretical frameworks, as the problem of implementation is also a problem of our own understanding of agency. Among the modes of recognition, rights are only a limited part of the reality experienced by children mainly in terms of affection and esteem. The challenges of implementing children’s participation rights in a series of settings, as recommended by CRC General Comment Nr 12, are therefore conveying an analysis of the terms used (maturity, freely expressed views, etc.) that may include children’s own perspectives on these issues. Examples of procedures for the implementation of children’s participation rights highlight all these challenges and the difficulties of defining good indicators of child participation. Besides, child participation should also be guaranteed even when children are viewed as “deviant” or “delinquent”: the respect for child participation in judicial settings highlights the complex interplay between one’s status and one’s rights in practice. Eventually, as child participation should be guaranteed in all settings, research itself should be child-friendly and participative and ethical principles for researchers must be specified when dealing with children.