Biodiesel can be produced from multiple oil and fat feedstock sources. Most of the nonedible oil sources have the potential to produce biodiesel at low cost. Unfortunately, they have more than 3% of free fatty acid (FFA), which pose challenges in the biodiesel production process via the homogeneous base transesterification. This calls for different FFA pretreatment methods prior to transesterification. Three potential technologies for chemical modification of high FFA in biodiesel feedstock have been presented in this chapter. This chapter also analyzes the potential and challenges of using various high FFA feedstock for biodiesel production.