Elizabeth Robertson is Professor of Developmental Biology at University of Oxford. She helped establish the first ES cell lines and showed they colonized the mouse germ line. Retroviral vectors were exploited to generate random mutations, and her subsequent phenotypic screens led to the cloning of Sry and identified the nodal gene. Liz edited the best-selling “Teratocarcinomas and Embryonic Stem cells: a Practical Approach”, spent 10 years as an Instructor at the CSH Mouse Course, and provided cell lines and advice to help make ES cell technology available to investigators around the world.