Synapses are crucial for communication among neurons in the central nervous system. Contactin-associated protein- like 2 (Caspr2) is a neuronal protein that is a member of the neurexin superfamily and is found in the juxtaparanodal regions of myelinated axons. Caspr2 has also been found in synapses and therefore is also thought to function as a cell adhesion molecule. As such, it should also induce synaptogenesis in vitro similar to the interaction between neurexins (located presynaptically) and neuroligins (located postsynaptically). Neurexins and neuroligins are calcium-dependent cell adhesion proteins that mediate the signaling across synapses and have the ability to affect the neuronal network by promoting the formation of excitatory or inhibitory synapses. Mutations in neurexins and neuroligins have been implicated with autism and autism spectrum disorders, among other neurodevelopmental disorders. As a member of the neurexin superfamily, Caspr2 shares the same increased risk for autism. Here I describe a co-culture experiment with rat hippocampal neurons and Caspr2-expressing HEK293 cells to test for synapse formation and its location in particular synapse sub-types