Mice were kindled to produce minimal convulsions by repeated application of either electrical or chemical stimuli. Electrical kindling involved the use of corneal electrodes; chemical kindling involved the use of pentylenetetrazol or picrotoxin. Delta-9-tetrahydrocannabinol (delta-9-THC) appeared to be capable of enhancing kindling to all three stimuli. In the studies with electroshock and pentylenetetrazol, in contrast to those with picrotoxin, a single exposure to delta-9-THC sufficed to facilitate the subsequent kindling, and the enhancement of kindling persisted after withdrawal of the cannabinoid. In the case of electrical kindling, the cannabinoid may promote the phenomenon by decreasing the convulsion threshold. Because the threshold was not lowered to all kindling stimuli, however, other mechanisms must be involved. In general, the data indicate that even a single dose of delta-9-THC can promote the development of long-lasting elevations of CNS excitability.