Most synapses are made onto dendrites, and most excitatory connections are made onto dendritic spines. Synaptic plasticity is thus an intrinsically dendritic phenomenon, but the functional significance of the structural, electrical, and molecular properties of dendrites for synaptic plasticity is still very poorly understood. Do dendrites have a computational or cell biological role in the modification of synaptic strength that is more than circumstantial? This chapter aims to summarize experimental data and theoretical considerations that may be relevant to the role of dendrites in synaptic plasticity. The focus is on associative Hebbian synaptic plasticity, including spike-timing-dependent forms, mediated by NMDA receptor activation.