The substantial increase in the scope of activities of Not for Profit Organizations (NPOs) is very challenging to their staff and management. Scarce resources and the increasing demand for accountability put pressure on NPOs to become more professional and more efficient. NPOs are expected to adopt modern management tools that are common in the business sector. On the other hand, NPOs have several unique characteristics that sometimes preclude a simple adoption of business models. Moreover, in many cases nonprofit activity, which by its nature is multidimensional, is more complex than business activity. There is clearly a need to develop and implement quantitative managerial methods that are adapted to the unique needs of NPOs. This book is my attempt to present several quantitative methods that were successfully implemented in a few organizations. The book addresses a variety of topics such as: resource allocation, performance, evaluation, and financial management. Nonprofits directors, board members and funders can find in this book some useful tools to improve the performance of their programs and organization.