Dynamic regulation of synaptic efficacy is one of the mechanisms thought to underlie learning and memory. Many of the observed changes in efficacy, such as long-term potentiation and long-term depression, result from the functional alteration of excitatory neurotransmission mediated by postsynaptic glutamate receptors. These changes may result from the modulation of the receptors themselves and from regulation of protein networks associated with glutamate receptors. Understanding the interactions in this synaptic complex will yield invaluable insight into the molecular basis of synaptic function. This review focuses on the molecular organization of excitatory synapses and the processes involved in the dynamic regulation of glutamate receptors.