Calbindin, also known as calbindin 1 or calbindin-D28k is a member of the large superfamily of cytoplasmic EF hand containing Calcium binding proteins and is expressed in the brain, intestine, kidney and pancreas. It is particularly concentrated in the dendrites and perikarya of cerebellar Purkinje cells, but is also found in many GABAergic interneurons in the cerebral cortex. These GABAergic interneurons in most cases express only one of three Calcium binding proteins, namely calbindin or parvalbumin or calretinin. As a result these important and physiologically distinct inhibitory interneurons can be identified and subclassified based on their content of these three proteins. The Calb antibody was made against full length recombinant human calbindin expressed in and purified from E. coli. We have shown that the antibody binds calbindin cleanly on western blots and in sections but fails to recognize the related calretinin and parvalbumin proteins. It is therefore ideally suited for identifying and subclassifying cortical GABAergic neurons.