ACFC/31DOC(2008)001 Article 17 and Article 1873 166. Article 17 (1) of the Framework Convention stipulates that State Parties shall not prevent persons belonging to national minorities from establishing and maintaining free and peaceful contacts across frontiers, in particular with persons belonging to the same national minorities. Article 17 (2) aims to ensure that persons belonging to national minorities can make an active contribution to civil society, at the national and international levels. 167. Like Article 17, Article 18 (2) encourages a proactive approach to transfrontier co-operation, but between States. Cross-border co-operation can significantly contribute to developing participation of persons belonging to national minorities in public affairs and in social, economic and cultural life. 73 17 (1) The Parties undertake not to interfere with the rights of persons belonging to national minorities to establish and maintain free and peaceful contacts across frontiers with persons lawfully staying in other States, in particular those with whom they share an ethnic, cultural, linguistic or religious identity, or a common cultural heritage. 17 (2) The Parties undertake not to interfere with the right of persons belonging to national minorities to participate in the activities of non-governmental organisations, both at the national and international levels. 18 (2) Where relevant, the Parties shall take measures to encourage transfrontier cooperation. 42