World organizations try to respond to the crucial problem of global climate change. According to the United Nations, sustainable development is in the centre of devising solutions to global problems. The aim of the United Nations 2030 Agenda is achieving sustainable development goals at a global scale in all aspects of life. Libraries are cultural and social centres and as such they can be used in order to achieve sustainable development goals according to the International Federation of Library Associations and Institutions (IFLA). IFLA works through the Environment, Sustainability and Libraries Section, which gives the IFLA Green Library Award to the best green libraries in the world. A green library is a green library building, but also a library which offers green services and organizes green projects. The first green library project in Croatia was devised by Društvo bibliotekara Istre in 2011. Until 2021, there have been many local and national green library programs and projects. The research in this thesis concerns whether green library projects have had an impact on green material acquisition. The research presents the green material representation in public library collections in Croatia. The thesis presents the data on green material linguistic diversity, the number of green materials for various age groups, the checkout history of green materials, and the green material acquisition trend. Twenty Croatian public libraries participated in the research.