The topic of this master thesis is the business of non-profit organizations which are focused on providing various forms of humanitarian aid and support, protection and promotion of human rights and the progress of our society. Although the goal of these organizations is not to make a profit, they are based on certain operating principles, organizational and management structure, sources of financing, marketing and communication strategies, vision and mission. The association of St. Jerome in Kaštel Gomilica is presented as a case study as it implements projects and programs intended for the most vulnerable social groups and continuously cooperates with other relevant organizations, institutions, local government and ministries in achieving their mutual humanitarian goals. Although non-profit organizations are sometimes subject to misuse and exploitation, this thesis emphasizes their value and importance as initiators of positive social change and the society would not be the same without them.