Activation of c‐fos in brain is related to coupling of neuronal activity to gene expression, but also to pathological conditions such as seizures or excitotoxicity‐induced cell death. Glutamate activates c‐fos in neurons through the calcium‐dependent phosphorylation of CREB by ERK and/or CaMKIV kinase pathways downstream NMDA‐receptors. In glial cells, however, the activation of c‐fos by glutamate is poorly understood. Because glial cells actively modulate neuronal excitability and the brain's response to injury, we studied the mechanisms by which glutamate activates c‐fos in rat cortical glial cells. Glutamate potently induced c‐fos mRNA in a calcium‐dependent manner, as demonstrated by using the calcium chelator BAPTA‐AM. Glutamate‐induced c‐fos mRNA expression was not sensitive to inhibitors of ERK, p38^MAPK, or CaMK pathways, indicating that glial c‐fos is activated by a distinct mechanism. Thapsigargin abolished the glutamate effect on c‐fos mRNA, indicating ER calcium mobilization. Additionally, glutamate induction of c‐fos mRNA was sensitive to the mGluR5 antagonist MPEP but not the NMDA‐R antagonist MK‐801. In luciferase reporter assays, DRE, which actively represses c‐fos by binding the calcium‐binding transcriptional repressor DREAM, was activated by glutamate, whereas SRE and CRE were not. Finally, glutamate caused the nuclear export of DREAM in astrocytes, and transfection of astrocytes with a mutant variant of DREAM that constitutively binds DNA inhibited glutamate‐induced c‐Fos expression. These findings are in sharp contrast to the mechanism described in neurons and suggest a novel pathway activated by glutamate in glial cells that employs mGluR5, ER calcium, and the derepression of c‐fos at the DRE. © 2006 Wiley‐Liss, Inc.