This chapter overviews clinically available and developmental contrast agents used in plaque imaging. The majority of plaque imaging experiments in humans has utilized small molecular weight gadolinium agents such as Gd-DTPA and Gd-DTPA-BMA. A target of molecular contrast agents in the investigation of atherosclerosis is factors influencing angiogenesis. A major alternative to gadolinium-based agents are ultrasmall particles of superparamagnetic iron oxides. Contrast-enhanced (CE)-magnetic resonance imaging (MRI) of atherosclerosis using gadolinium agents requires special considerations in the method of image acquisition. Although late phase enhancement has been shown to provide additional information for characterizing plaque composition, the major contributions of CE MRI were expected to be in quantification and identification of inflammation. Although standard gadolinium agents produce non-specific enhancement, they still provide considerable useful information for gauging atherosclerotic plaque. Contrast-enhanced T1-weighted images can serve as additional weightings in a comprehensive multicontrast evaluation of plaque composition.