A grant is essentially an investment and thus should maximize its returns and minimize its risks. However, the potential returns or potential impacts of a funded project are complex, with multiple types, dimensions, and levels. These make grant impacts a complex system. At the beginning of the grant process, we need to consider the funders’ mission, grant program purposes, grant objectives, or grantees’ motivations for a proposed project. At the end of the grant process, we need to consider project outputs, project outcomes, and eventually grant impacts for a funded project. Thus, the intellectual goal of this chapter is to understand the importance and complexity of grant impacts and to develop a systematic understanding of grant impacts to use as a guide for our professional grant practice.