Coronary angiography is the gold standard for the diagnosis of coronary artery disease and guides revascularization strategies. The emergence of new diagnostic modalities has provided clinicians with adjunctive physiologic and image-based data to help formulate treatment strategies. Fractional flow reserve can predict whether percutaneous intervention will benefit a patient. Intravascular ultrasonography and optical coherence tomography are intracoronary imaging modalities that facilitate the anatomic visualization of the vessel lumen and characterize plaques. Near-infrared spectroscopy can characterize plaque composition and potentially provide valuable prognostic information. This article reviews the indications, basic technology, and supporting clinical studies for these modalities.