Extracellular matrix molecules play important roles in neural developmental processes such as axon guidance and synaptogenesis. When development is complete, many of these molecules are down-regulated, however the molecules that remain highly expressed are often involved in modulation of synaptic function. SC1 is an example of an extracellular matrix protein whose expression remains high in the adult rat brain. Confocal microscopy revealed that SC1 demonstrates a punctate pattern in synaptic enriched regions of the cerebral cortex and cerebellum. Higher resolution analysis using electron microscopy indicated that SC1 localizes to synapses, particularly the postsynaptic terminal. SC1 was also detected in perisynaptic glial processes that envelop synapses.