Driven by advances in molecular probe design and biomarker detection methodologies, new imaging agents that can improve visualization of pathologies and cellular processes are changing the practice of diagnostic medicine. The ability of this new generation of contrast agents to detect metabolic changes at the molecular level has significant potential for improving visualization and quality of care. Targetable and activatable imaging agents are gaining interest for a wide range of diagnostic applications that include cardiology, neurology and soft tissue tumor detection. The number of healthcare conditions that can be effectively imaged noninvasively is expanding as a result of these innovative detection technologies. Targeted and activatable imaging agents offer a unique capability to generate unambiguous images by exploiting specific molecular targets, pathways or cellular processes. This new wave of imaging agents signals a paradigm shift in which the reagents take on new importance.