The Monteverde Conservation League (MCL) is a non-profit civil organization, whose mission is "to conserve, preserve, and rehabilitate tropical ecosystems and their biodiversity". The MCL organizes environmental education activities; and is involved with reforestation, scientific research, protection and management, sustainable development, and ecotourism. The MCL is also a founding member of the Red Costarricense de Reservas Privadas, and a member of the International Union for Conservation of Nature (IUCN).
The MCL has succeeded in creating the largest private reserve in Costa Rica: The Children's Eternal Rainforest (Bosque Eterno de los Niños or BEN), with an area of 22,500 hectares or 54,000 acres. This was made possible thanks to help from children, adults, schools, and organizations all over the world.