Despite recent progress in the treatment of cancer, far too many cases are still diagnosed only after tumors have metastasized. As a result, patients with cancer face a grim prognosis and often need to endure toxic and uncomfortable whole-body chemotherapy and/or other radiation treatments with the hope that their cancers will be eliminated. If the disease can be detected early enough, statistics have shown that the burden of cancer is drastically reduced. Nanotechnology applied to cancer, by way of nanofunctional materials, is in a unique position to significantly transform the way the disease is diagnosed, imaged, and treated and is the focus of this issue of MRS Bulletin. Materials research in nanotechnology is already successfully implemented in several applications. For instance, photocatalysis using TiO2 nanoparticles is becoming the dominant method for the “self-cleaning” of material surfaces such as glass, ceramics, and fabrics. The nanomaterial carbon nanotubes is a promising candidate in sensor technology and field-emission technology. Our goal is to illustrate the promising new methods being developed in the research community and the challenges that need to be overcome in order to reach clinical utility. More importantly, we hope this issue helps educate and invoke the materials science community to tackle some of the hard issues in diagnosing and treating this disease.