This chapter considers the development of safe and sensitive chemical exchange saturation transfer (CEST) contrast agents for MRI. CEST MRI is a contrast mechanism that enables the amplified detection of solutes based on the exchange of their labile protons with water. This chapter describes the general theory of CEST agents and their practical uses. Consideration is then given to the acquisition of CEST spectra, including instrumentation, sample conditions and data analysis, as well as the determination of the number of inner-sphere water molecules (q) for metal-based CEST complexes and proton exchange rates (kex). The preparation and characterization of paramagnetic micelles and liposomes is also discussed as well as the acquisition of CEST MR phantom images.