This book considers the Optional Prool to the Convention on the Rights of the Child on a communication procedure as a key contributor to the realization of children’s Article 12 Convention on the Rights of the Child participation rights. Weaknesses in the current formulation of the CRC communication procedure (its first iteration since entry into force 14 April, 2014) are examined and suggestions for strengthening of the mechanism in various respects considered. Actual cases concerning children’s fundamental human rights in various domains and brought under various international human rights mechanisms are considered as hypothetical OP3-CRC communications/complaints. In addition certain domestic cases brought to the highest State Court are considered as hypothetical OP3-CRC communications brought after exhaustion of domestic remedies. In this way various significant weaknesses of the OP3-CRC are illustrated in a compelling meaningful case context and needed amendments highlighted.