Abstract: A contrast agent for magnetic resonance imaging having a plurality of nanoparticles. Each of the nanoparticles has: a signal generating core having a diameter of up to 10 nm; at least one organic layer of at least one of a polymer, a monomer, and a surfactant; and a water soluble outer shell of at least one of a polymer, a monomer, and a ligand. The organic layer is adsorbed upon and substantially surrounds and stabilizes the signal generating core. The water soluble outer shell solubilizes and provides biocompatibility for each of the nanoparticles. The contrast agents provide enhanced relaxivity, high signal-to-noise ratios, and targeting abilities. In addition, the contrast agents possess resistance to agglomeration, controlled particle size, blood clearance rate, and biodistribution. Methods of making such contrast agents and nanoparticles are also disclosed.