Functional glutamate receptors are expressed on the majority of glial cell types in the developing and mature brain. Although glutamate receptors on glia are activated by glutamate released from neurons, their physiological role remains largely unknown. Potential roles for these receptors in glia include regulation of proliferation and differentiation, and modulation of synaptic efficacy. Recent anatomical and functional evidence indicates that glutamate receptors on immature glia are activated through direct synaptic inputs. Therefore, glutamate and its receptors appear to be involved in a continuous crosstalk between neurons and glia during development and also in the mature brain.