Bill Evans and Jim Hall had first recorded together in July of 1959, during the making of John Lewis' LP Odds Against Tomorrow, and the two musicians also participated on Gunther Schuller's Jazz Abstractions (recorded in December of 1960). However, those were big band albums and had no space at all for any real interaction between the pianist and guitarist. Undercurrent, presenting them as a duet, was their third studio encounter and one of their most rewarding collaborations.