Mr. P.C. was composed by John Coltrane in 1959 as a tribute to bassist Paul Chambers, whose initials form the title. The tune was recorded on May 4, 1959, during the sessions for Coltrane's landmark Atlantic Records debut Giant Steps, with Tommy Flanagan on piano, Chambers himself on bass, and Art Taylor on drums. At the time of the recording, Coltrane was still officially a member of the Miles Davis Quintet but had recently signed his first major contract as a leader. The composition sits alongside the harmonically adventurous title track and Countdown on the same album, yet it takes a deliberately simpler approach rooted in the blues tradition. Its directness has made it one of the most widely called tunes at jam sessions, with musicians reportedly needing only to shout the initials P.C. to launch into an impromptu performance. The tune has also found a home in jazz education, with published arrangements for young ensembles by arranger Terry White among others. In an unusual footnote, the rock band Phish incorporated Mr. P.C. into their live repertoire beginning in July 1988, performing it sporadically through 1991. One particularly memorable Phish rendition occurred during a power outage at the Campus Club on May 17, 1991, when an electrical failure forced an improvised drum and trumpet jam that spontaneously evolved into Mr. P.C. until power was restored. The composition endures as an essential part of the jazz canon, bridging Coltrane's advanced harmonic explorations with the deep roots of the blues.