High altitude air breakdown, manifested as red sprites, is reported in close association with negative cloud-to-ground lightning (-CG) on at least two occasions above an unusual storm on August 29, 1998. Data from high speed photometry, low-light-level video, and receivers of lightning electromagnetic signatures in the frequency range 10 Hz to 20 kHz are used to establish the association and indicate that the causative -CG discharges effected unusually large vertical charge moment changes (ΔMQv) of up to 1550 C⋅km in 5 ms. The existence of sprites caused by -CG's, rather than the regularly associated +CG's, has immediate implications for sprite models and observations. ¿ 1999 American Geophysical Union