Nitrogen is one of the most essential elements for life. It has been used to synthesize essential molecules such as amino acids and nucleotides in the construction of life. Consequently, nitrogen-containing compounds have important roles in all fields of chemistry, and in all aspects of life in living organisms. The N-alkylation of amines constitutes one of the most widely applied transformations in synthetic chemistry, but established methods often utilize non-renewable feedstocks and must be adapted for a post-fossil fuel world. This chapter is focused on emerging methodologies for N-alkylation and considers challenges in the applications of amines and the development of sustainable methodologies.