Cover Legend Fully hydrated Staphylococcus epidermidis biofilm imaged by confocal microscopy showing microcolonies (yellow clusters) and extracellular matrix material (red). Each microcolony contains thousands of bacteria. See related article by Stewart et. al., Biotechnology and Bioengineering, Volume 108, Number 12 (December 2011), pages 2968–2977. (Image courtesy of Betsey Pitts, Willy Davison, Paul Perry and Phil Stewart).