William Weis was born and grew up in Queens, New York, the youngest of three brothers. His grandparents immigrated from Ukraine, Belarus, and Latvia, ultimately settling in Brooklyn, New York. A "frustrated architect," his father was in the United States Merchant Marines in World War II, where he learned electronics; he later earned a degree in electrical engineering at Brooklyn Polytechnic (now Polytechnic Institute of New York University) and worked in vacuum tubes until technology passed them by, at which time he began work for the New York City Office of Management and Budget. Weis's mother was an administrator in a volunteer social work agency and the administrator of a close family. Weis always liked learning and school. He especially liked mathematics and science, even reading his older brother's entire anatomy textbook when he (William) was in sixth grade. In eighth grade he took a class of biology and chemistry together and fell in love with biochemistry. In high school he took two science classes every year and was on the math team. Since a broad base of learning was important to him, Weis knew he wanted to attend a liberal arts college that also had strong science. He was accepted at Princeton University, and although it was financially difficult for his parents, he did go there and loved it. He majored in biochemistry and discovered spectroscopy, writing his graduation thesis on rhodopsin spectroscopy. Because DNA sequencing was new, many others went into molecular biology, but Weis liked physical chemistry best. He worked in Meredithe Applebury's lab, and she and Zoltan Soos were his major influences. For graduate school Weis wanted a strongly quantitative school and one large enough to have a choice of labs. Matriculating into Harvard University, Weis liked all his rotations, but he found Don Wiley's crystallography lab perfect for him. Wiley was doing fascinating work and was extremely enthusiastic about science. There he worked on influenza hemagglutinin. When he finished his PhD he decided to spend a year at Yale University, working with Axel Brünger on simulated annealing, getting a better model of hemagglutinin. From there he went to Columbia University Medical Center, to Wayne Hendrickson's lab, where he spent the "best four years of [his] life" studying the structure of C-type lectins using MAD phasing (multiwavelength anomalous scattering phasing or dispersion). He accepted an assistant professorship at Stanford University, taking his research with him. In addition to managing his lab with its different personalities, he teaches some and has a few administrative duties. He likes writing papers and does not mind writing grants, of which he has received several. He has achieved tenure. He loves his work and spends most days in the lab, though he also takes time for his girlfriend. He feels he has met his goals so far, especially his professional goals. He thinks he would someday like to do community work, perhaps science education in earlier grades, particularly among minority students. His current research comprises three areas: the C-type lectins; an interest in cell adhesion, specifically cadherins (calcium-dependent adhesion molecules); and intracellular vesicle trafficking.