A variety of Ca~(2+)signals,in the form of intercellular pulses and waves,have beenreported to be associated with the various sequential stages of somitogenesis:from convergent extension and the formation of the paraxial mesoderm;during thepatterning of the paraxial mesoderm to establish segmental units;throughout theformation of the morphological boundaries that delineate the segmental units,andfinally from within the maturing somites as they undergo subsequent develop-ment and differentiation.Due to both the technical challenges presented in imag-ing intact,developing embryos,and the subtle nature of the Ca~(2+)transientsgenerated,they have proved to be difficult to visualize.However,a combinationof cultured cell preparations and improvements in explant and whole embryo im-aging techniques has begun to reveal a new and exciting class of developmentalCa~(2+)signals.In this chapter,we review the small,but expanding,number ofreports in the literature and attempt to identify common characteristics of thesomitogenic Ca~(2+)transients,such as their mode of generation,as well as theirspatial and temporal features.This may help to elucidate the significance andfunction of these intriguing Ca~(2+)transients and thus integrate them into the com-plex signaling networks that orchestrate early developmental events. A variety of Ca ~ (2+) signals, in the form of intercellular pulses and waves, have been reported to be associated with the various sequential stages of somitogenesis: from convergent extension and the formation of the paraxial mesoderm; during the patterning of the paraxial mesoderm to establish segmental units; throughout theformation of the morphological boundaries that delineate the segmental units, andfinally from within the maturing somites as they occur later develop-ment and differentiation. Due to both the technical challenges presented in imag-ing intact, developing embryos, and the subtle nature of the Ca 2+ transients generated, they have proved to be difficult to visualize. Yet, a combination of cultured cell preparations and improvements in explant and whole embryo im-aging techniques has begun to reveal a new and exciting class of developmentalCa ~ (2+) signals.In this chapter, we review the small, but expanding, number ofreports in the literature and attempt to identify common chara cteristics of the somitogenic Ca ~ (2+) transients, such as their mode of generation, as well as theirspatial and temporal features.This may help to elucidate the significance andfunction of these intriguingCa ~ (2+) transients and thusintegration them into the com-plex signaling networks that orchestrate early developmental events.