Our brain and nervous system coordinate all activities of ourbody and its interaction with the environment. Our brain ismade up of a large number of cells called neurons that formspecialised points of contacts with other neurons. These contactsare called synapses. The development and functioningof these synapses are clearly vital for nervous system function.A set of molecules call Cell Adhesion Molecules (CAMs)have been shown to be required for the development and maintenanceof synapses. More recent work with CAMs indicatesthat these molecules are also required for signalling andhence normal functioning of synapses. Here, I discuss howCAMs function both in normal synapse development and insignalling at the synapse.