(b Chicago, September 1959). American acid house producer and musician. He was first attracted to dance music in 1983 at Chicago's Music Box on hearing early influential DJs such as Ron Hardy and the ground-breaking early house music of Jesse Saunders. Using the most basic of instrumentation, he recorded classic examples of early Chicago house music; his début, Go Wild Rhythm Trax (1985), paved the way for Move Your Body, acknowledged as one of house music's most important works. He then produced Acid Trax (1988) for Phuture which, in using the sound of the Roland TB-303 synthesizer, created the acid house genre; both the track and genre spawned more imitators than developers of the sound, something which drove Jefferson back underground to record the sweeping, less TB-303-oriented Open your eyes. This attempt to recreate his early feelings for Chicago house led to ‘deep house’. He also put together and produced the vocal dance group Ten City throughout the late 1980s and early 90s. Despite the solo album Day of the Onion (KTM? 1997), his defining work remains restricted to an intensely creative and inspiring period in the late 1980s.