The field program of the thunderstorm Electrification and Lightning Experiment (TELEX) took place in central Oklahoma, May-June 2003 and 2004. It aimed to improve understanding of the interrelationships among microphysics, kinematics, electrification, and lightning in a broad spectrum of storms, particularly squall lines and storms whose electrical structure is inverted from the usual vertical polarity. The field program was built around two permanent facilities: the KOUN polarimetric radar and the Oklahoma Lightning Mapping Array. In addition, balloon-borne electric-field meters and radiosondes were launched together from a mobile laboratory to measure electric fields, winds, and standard thermodynamic parameters inside storms. In 2004, two mobile C-band Doppler radars provided high-resolution coordinated volume scans, and another mobile facility provided the environmental soundings required for modeling studies. Data were obtained from 22 storm episodes, including several small isolated thunderstorms, mesoscale convective systems, and supercell storms. Examples are presented from three storms. A heavy-precipitation supercell storm on 29 May 2004 produced greater than three flashes per second for 1.5 h. Holes in the lightning density formed and dissipated sequentially in the very strong updraft and bounded weak echo region of the mesocyclone. In a small squall line on 19 June 2004, most lightning flashes in the stratiform region were initiated in or near strong updrafts in the convective line and involved positive charge in the upper part of the radar bright band. In a small thunderstorm on 29 June 2004, lightning activity began as polarimetric signatures of graupel first appeared near lightning initiation regions.