Nonprofit operations management has gained increasing attention from both academia andpolicymakers. While the literature has focused on monetary donations, it is important to recognize that individuals also support charity organizations through volunteering and in-kind gifts. This dissertation examines the role of in-kind donations in supporting the operations of Nonprofit organizations. It is divided into three pieces: the first two investigate the relationship between individuals’ time and monetary donations, and their implications for Nonprofit operations, while the last part centers on individuals’ goods donations. The first chapter explores a fundamental question: Do volunteering activities discourage or encourage donations? While some research suggests that people view their time and financial contributions as substitutes, others believe that they should be complementary. Two controlled online experiments indicate that volunteering improves subsequent monetary donations and that, as greater effort is required, people tend to reduce their donations. These results highlight the importance of considering both the labor and financial contributions of volunteers and creating volunteer projects with an appropriate level of effort. The second chapter is about how to manage volunteers, taking into account how volunteers can be unpredictable, heterogeneous, and even donate money. The results challenge conventional knowledge in volunteer management, highlighting the need to integrate the management of volunteers and donors. Volunteers are not only suppliers of labor, but also consumers of volunteering activities. Moreover, enhancing the job efficiency of volunteers may also hinder the performance of charities. Last, the donation of goods is a vital form of supply for charities, which can be resold to generate additional revenue. However, not all in-kind gifts are useful, and unwanted donations can place a financial strain on charitable organizations. Despite this, nonprofits may hesitate to reject undesired donations for fear of discouraging future support. In response, I employ behavioral interventions to encourage donors to voluntarily increase the quality of their gifts.