Excitatory synaptic transmission in the central nervous system mainly takes place at dendritic spines, highly motile protrusions on the dendritic surface. Depending on the stimuli received, dendritic spines undergo rapid actin-based changes in their morphology. This plasticity appears to involve signaling through numerous proteins that control the organization of the actin cytoskeleton (actin regulators). At least in part, recruitment and activation of these depends on neurotransmitter receptors at the post-synapse, which directly link neurotransmission to changes in dendritic spine architecture. However, other, non-neurotransmitter-receptors present at dendritic spines also participate. It is likely that several receptor types can control the activity of a single actin-regulatory pathway and it is the complex integration of numerous signals that determines the overall architecture of a dendritic spine.