Constricted discharges have been produced in krypton using both pulsed and dc excitation over a total pressure range of 8–120 torr. Light-flux, voltage, and current waveforms were obtained for the pulsed discharge and interpreted in terms of electron excitation and electron–ion recombination processes. Streak-camera photography was used to observe possible changes of the degree of constriction during the pulse and afterglow periods. Detailed profile analysis of spectral lines yielded a value of 380±50 K for the discharge temperature and evidence was found of Stark effects. A new model for the discharge mechanism is proposed, in which diffusion of electrons and ions from the central glowing core is balanced by recombination in the peripheral regions of lower charge density and lower excitation.