The integrin leukocyte function-associate antigen 1 (LFA-1) is pivotal for cell adhesion and signalling within the immune system. Here, Minke Binnerts and Yvette van Kooyk discuss evidence from mutational and crystallographic studies showing that binding of LFA-1 to its ligands intercellular adhesion molecule 1 (ICAM-1), -2 and -3 might be structurally distinct.