Magnetic resonance imaging (MRI) is a clinical diagnostic technique employing a variety of contrast mechanisms, some of which are reliant upon the mapping of differential water proton relaxation following radiofrequency excitation in a magnetic field.  MRI has traditionally been applied to anatomical and functional imaging in the clinical setting, and has been moving toward molecular-level diagnosis in part through the use of biochemical-targeted contrast agents. Gadolinium-based chelates that reduce the relaxation time of neighboring water protons have previously been the focus of contrast agent development, however concerns about chelate stability in vivo has motivated a search for metal-free alternatives. Chemical Exchange Saturation Transfer (CEST) using organic (i.e. diamagnetic) probes is a recently proposed metal-free MRI technique offering a promising alternative mode of molecular-level contrast that can overcome the toxicity concerns associated with paramagnetic agents. In the Molecular Medicine Lab, we are exploring new chemistry enabling the development of conditional CEST contrast agents that only produce imaging signal when activated by biomolecular targets of interest.