Biointerface science, defined as the study and control of biomolecular interactions at surfaces, is a critical component of many aspects of biotechnology, but it has only recently begun to attract the attention it deserves as a unique interdisciplinary research area. This issue of MRS Bulletin explores the rich diversity of function provided by biomolecules at interfaces and the unparalleled opportunities for applications, which range from clinical diagnostics, biomaterials, and tissue engineering to genomics and proteomics. This diversity will continue to drive the evolution of biointerface science.