When plant cells are exposed to environmental stresses or perceive internal signal molecules involved in growth and development, ion channels are transiently activated to convert these stimuli into intracellular signals. Among the ions taken up by plant cells, Ca²⁺ plays an essential role as an intracellular second messenger in plants; the cytoplasmic free Ca²⁺ concentration ([Ca²⁺]_c) is therefore strictly regulated. Signal transduction pathways mediated by changes in [Ca²⁺]_c – termed Ca²⁺ signaling – are initiated by the activation of Ca²⁺-permeable channels in many cases. To date, a large body of electrophysiological and recent molecular biological studies have revealed that plants possess Ca²⁺ channels belonging to distinct types with different gating mechanisms, and a variety of genes for Ca²⁺-permeable channels have been isolated and functionally characterized. Topics in this chapter focus on long-distance signal translocation in plants and the characteristics of a variety of plant Ca²⁺-permeable channels including voltage-dependent Ca²⁺-permeable channels, cyclic nucleotide-gated cation channels, ionotropic glutamate receptors and mechanosensitive channels. We discuss their roles in environmental responses and in the regulation of growth and development.