Organizations of the different sectors of economy are characterized by a growing number of similar features. So, nonprofit organizations become in certain respect similar to business sector organizations. This is a phenomenon that brings for them opportunities, but also risks and challenges. In connection with it, a need develops to change, to improve existing structures and processes, to become innovative organizations, to use the tools of managerialism. The paper is based dominantly on international research of the last decade and on the ongoing research of the authors in the field of professionalization of nonprofit organizations. It gives a critical overview of a variety of issues in connection with it. Literature analysis is supported by evidence from the practice to show how nonprofit organizations are learning new managerial and leadership skills and acquiring new knowledge in order to meet challenges of an uncertain environment. Through this, the paper contributes to current research in this field; and gives insight in certain changes connected to the need of nonprofit organizations to become more professional in their operations.