This chapter focuses on the enzymes and proteins involved in the regulation of juvenile hormone (JH)Juvenile hormone (JH) activity through degradation and transport. Degradative enzymes play a critical role in rapidly “switching off” hormone activity in specific organs or throughout the body, in coordination with the cessation of biosynthesis. In contrast, JH-binding proteins (JHBPs) in the hemolymph are essential for facilitating the transport of JH from its site of biosynthesis, the corpus allatum, to target organs and tissues in the form of a JH–JHBP complex. This complex protects JH from nonspecific degradation by hydrolytic enzymes, such as general esterases, present in the hemolymph. Once JH reaches its target organs or tissues, it binds to the JH receptor to elicit biological responses in the target cells. In this chapter, the functions, characteristics, and regulatory mechanisms of these enzymes and proteins are discussed.