Voltage-gated calcium (Ca2+) channels are ubiquitous in excitable cells, and intracellular Ca2+ transients, in which the channels play key roles, trigger many physiological events. At this time, 10 members of the voltage-gated Ca2+ channel family in mammals are recognized, and they play diverse roles in the signal transduction system. The CaV1 subfamily (L-type) is involved in contraction, secretion, integration of synaptic input in neurons, regulation of gene expression, and, in specialized sensory cells, synaptic transmission at ribbon synapses. The members of the CaV2 subfamily (P/Q-, N-, and R-types) initiate synaptic transmission at fast synapses. The CaV3 subfamily is important in rhythmically firing cells such as cardiac nodal cells and thalamic neurons. The channels in this family are essential for the cyclic firing of action potentials. This article summarizes the relationships between the molecular and physiological functions of these Ca2+ channel proteins.