The static levels of proteins are the net results of their production and clearance regulated by the activities of proteins involved in their synthesis, degradation, and transportation. Therefore, the information on the rates of protein synthesis and clearance is needed to understand the underlying dynamic nature of a proteome. In this chapter, the experimental technique, we use in our laboratory for monitoring the synthesis of individual proteins in Caenorhabditis elegans (C. elegans) is described. The technique utilizes a preisotopically labeled amino acid (13C6-Lys) as a precursor for protein synthesis and monitors the kinetics of the precursor incorporation into the newly synthesized proteins. C. elegans is a powerful animal model in various fields of biomedical science such as aging, developmental biology, and neurobiology. The experimental technique would, therefore, be useful for research laboratories using C. elegans as an animal model.