Histopathological examination of culprit plaques in sudden coronary death has long suggested that accurate in vivo determination of plaque composition may be of equal or greater importance to future coronary event risk assessment as plaque cross-sectional size or volume. Intracoronary near-infrared spectroscopy (NIRS) was developed to detect the most prominent compositional feature of a thin-capped fibroatheroma—the presence of a lipid core. The need for invasive, focal coronary imaging techniques, the added value of compositional measures, and the applicability and principles of operation of intracoronary NIRS are described. Additionally, a combination device with NIRS and simultaneous, co-registered intravascular ultrasound (IVUS) is described, which gives complementary structural and compositional measures. The identification and morphological assessment of lipid core plaque with NIRS-IVUS has potential to improve the safety of stenting, including optimization of length of vessel to stent, assurance of adequate stent deployment, and identification of lipid-core lesions at higher risk of distal embolization possibly leading to effective utilization of distal embolic protection devices in the native coronaries. The NIRS-IVUS device also has promise in the identification of vulnerable plaque, which may lead to strategies to prevent future coronary events.