Investigators are beginning to define the chemical circuitry of certain elements of the cerebral cortex. In this article we review some of the recent findings on the morphological distribution and cellular effects of monoamines (principally noradrenaline) and peptides (principally vasoactive intestinal peptide) in neocortex. The transmitter-specific anatomical methods establish the morphological constraints of the functional circuits within which the cellular effects must take place. Noradrenaline (NA) and vasoactive intestinal peptide (VIP) are discussed as examples of neurotransmitters which share at least one important cellular effect on cortex (activation of glycogenolysis) but have very different anatomical constraints