Fully biobased lubricants are those formulated using all biobased ingredients, that is, biobased base oils and biobased additives. Such formulations provide the maximum environmental, safety, and economic benefits expected from a biobased product. Currently, there are a number of biobased base oils that are commercially available or will be available in a very short time. However, there are no commercial biobased additives to be used for obtaining fully biobased formulations. As a result, formulators are forced to use petroleum-based additives with the biobased base oils to produce partially biobased products. In an effort to remedy this situation, a number of research groups are engaged in the development of biobased additives. In this chapter, the authors summarize their effort at developing the following biobased additives: friction modifiers, biosurfactants, antiwear, viscosity index improvers (VIIs), antioxidants, and extreme pressure (EP). The effort involves the synthesis, identification/characterization, and evaluation of physical and tribological properties relative to commercial petroleum-based products. Based on the work to date, the current status of biobased additive development can be summarized as follows: (1) some biobased additives are ready for commercialization in the very near future; (2) several others will require more effort before they are competitive in performance to petroleum-based products; and (3) development work has yet to begin on a large number of biobased additives.