CVD diamond—Research, applications, and challenges. This issue of MRS Bulletin introduces the latest research, recent applications, and the challenges ahead for chemical vapor deposited (CVD) diamond films. The advent of thin nanocrystalline CVD diamond (NCD) films has unlocked a whole new research field. Based on the unique properties of diamond, a versatile range of new applications is currently being studied. The cover image shows a series of ultrathin NCD membranes, 150 nm thick and 550 μm wide, fabricated in the middle of a Hall bar structure and supported by a glass substrate, under differential pressures. The top 50 nm of these structures are heavily boron-doped, making them conducting and suitable as pressure sensors for harsh environments based on the piezoresistive effect, leading to resistance changes as a function of the pressure applied to the membrane. The differential pressures under the membrane vary from 0 bar in the top image to 0.55 bar in the bottom image. See the technical theme that begins on page 490.