Calcium entry into neuronal cells through voltage or ligand-gated ion channels triggers neuronal affinity-dependent gene expression critical for adaptive changes in the nervous system(1-5). Cytoplasmic calcium transients are often accompanied by an increase in the concentration of nuclear calcium(6-9), but the functional significance of such spatially distinct calcium signals is unknown. Here we show that gene expression is differentially controlled by nuclear and cytoplasmic calcium signals which enable a single second messenger to generate diverse transcriptional responses, We used nuclear microinjection of a nondiffusible calcium chelator to block increases in nuclear, but not cytoplasmic, calcium concentrations following activation of L-type voltage-gated calcium channels, We showed that increases in nuclear calcium concentration control calcium-activated gene expression mediated by the cyclic-AMP-response element (CRE), and demonstrated that the CRE-binding protein CREB can function as a nuclear calcium-responsive transcription factor. A second signalling pathway, activating transcription through the serum-response element (SRE), is triggered by a rise in cytoplasmic calcium and does not require an increase in nuclear calcium.