The excitatory transmission between neurons mostly relies on the activation of postsynaptic glutamate receptors. Over the last decade, it became clear that a way to modulate the excitatory synaptic transmission is to change the number of these receptors at the postsynaptic membrane. However the mechanisms by which such process can be achieved remain unclear. It recently emerged that glutamate receptors in addition to cycle between intracellular and membrane compartments, diffuse within the plasma membrane. In this lecture, I will describe our current understanding on the surface diffusion of glutamate receptors and what does it tell us about the synaptic maturation process.