Pilson was born in Lake Forest, Illinois and spent part of his youth in Milwaukee, Wisconsin before moving to Longview, Washington, where he graduated from R.A. Long High School in 1976. He attended the University of Washington to study music after he had started playing bass at age 13 but left without a degree in order to pursue a career in music. One of his early bands was an Emerson, Lake & Palmer type progressive trio called Christmas. He moved to San Francisco in 1978 where he met up and became friends with guitarist Mike Varney. Varney and Pilson would join forces in the band Cinema. After moving back to Seattle for a brief period, Varney called Pilson to get involved in the recording of "Rock Justice", a rock opera co-written by Varney and produced by Marty Balin.