This document discusses library cooperation between Poland and Lithuania through sister library partnerships. It provides examples of projects undertaken by sister libraries, such as the "Following the Footsteps of the Insurgents 1863 in Lithuania" project led by the Kaunas County Public Library and Municipal Public Library in Piekary Śląskie. The document outlines the benefits of sister library partnerships, including opportunities for professional development, cultural exchange, and program sharing. User feedback on sister library initiatives has been very positive.