Rustan Leino is a Principal Researcher at Microsoft Research, where his research centers around programming tools. He is currently working on the design and implementation of the Spec# programming language and its static program verifier. Before joining Microsoft Research, Leino worked as a researcher at DEC/Compaq SRC, where among other things he led the Extended Static Checking for Java (ESC/Java) project, a program checker built on the technology of program verification. His PhD thesis from Caltech (1995) addressed an important specification problem in ESC/Modula-3. Before going to graduate school, Leino worked as a software developer and technical lead in Windows/NT at Microsoft. He has written code that shipped in releases of Windows 3.0, Windows 3.1, and Windows/NT 3.5. In his spare time, he plays and records music, teaches step aerobics, and spends time with his wife and four children.