The Medical Research Council Laboratory of Molecular Biology in Cambridge played a key role in the postwar history of molecular biology. The paper, focussing on the early history of the institution, aims to show that the creation of the laboratory and the making of molecular biology were part of a new scientific culture set in place after World War II. In five interlinked parts it deals with the institutional creation of the MRC unit dedicated to the crystallographic analysis of biological (...) molecules; the attraction of postwar biophysics, the heading under which the work of the unit initially fell; the people who joined the laboratory and their appropriation of new technologies, in particular the electronic computer for protein crystal structure determination; the cultural appeal of postwar crystallography, as exemplified in the use of crystal structure diagrams for a wide series of consumer goods at the Festival of Britain in 1951 and the display of molecular models at the Brussels World’s Fair in 1958, a key site for the presentation of science and its role in the postwar world. (shrink)