The quartet of musicians that appear on the album had been playing together for four years at the time of the recording sessions, and was thus one of the longer-lived bands of Monk's career.

Allmusic's Lindsay Planer called the album "some of the finest work that Monk ever did in the studio with his '60s trio and quartet.

"[2] The critical and popular success of the group during this period led to Monk's appearance on the cover of Time magazine in February 1964.

It later became known that as Monk's international profile was reaching its apex in the mid-1960s, his manic depressive episodes were getting more severe and his composing output was diminished.

"Eronel" is a distinctly bop tune that is fast-paced and showcases Monk's virtuosic piano playing.