Mass spectrometry (MS) has experienced tremendous growth throughout numerous scientific disciplines in the last few decades. This chapter will provide a concise summary of informative topics related to the study of therapeutic agents by MS. Our objective is to highlight as many pertinent MS techniques as possible. However, it should be noted that this will not be an all‐inclusive list of approaches due to the large volume of literature. This chapter will be primarily divided into the areas of instrumentation, sample preparation, and applications in proteomics, metabolomics, and emerging fields in drug analysis.