Cell adhesion molecules mediate attachment of cells to each other and extracellular matrices. The adhesion strategies used by mammalian cells and cells from relatively simple organisms such as the nematode worm are remarkably similar. The latter therefore provides an extremely useful model system for analysing adhesion. In a Commentary on p. 1885, Elisabeth Cox and Jeff Hardin discuss recent work that has significantly increased our understanding of cell adhesion in nematodes and how this is providing insight into the process in vertebrates. In an accompanying Cell Science at a Glance piece, Cox et al. survey the known C. elegans adhesion molecules, revealing their domain structures and relatives in vertebrates (see p. 1867 + poster).