Silk fibroin derived from silkworm cocoons is finding increasing use in regenerative medicine and bio-sensing. Several methods for tailoring the material to specific uses currently exist, including electrospinning and electrogelation. On page 257, Mark Cronin-Golomb and colleagues demonstrate the ability to use light as an additional means of silk engineering thereby widening the range of applications to include optical sensing, optical information storage, and optical tuning of tissue engineering scaffolds. The optical sensitivity made possible by azo modification of the silk has high enough spatial resolution to enable holographic recording. The cover image shows reconstruction of a holographic image recorded in a thin film of azo modified silk fibroin. The curved lines around the image result from refraction through the wavy piece of silk that was used in the experiment. Azo-modified silk retains biocompatibility and may be suitable for use in implantable optical sensors and optically patterned substrates for tissue engineering.