Brian Jones, the band's founder and early leader, had become increasingly unreliable in the studio due to his drug use, and it was the last Rolling Stones album to be released during his lifetime, though he also contributed to two songs on their next album "Let It Bleed", which was released after his death. (Jones did, however, contribute to the group's hit song "Jumpin' Jack Flash", which was part of the same sessions, and released in May 1968.) Nearly all rhythm and lead guitar parts were recorded by Keith Richards, the Rolling Stones' other guitarist and the primary songwriting partner of their lead singer Mick Jagger; together the two wrote all but one of the tracks on the album. Rounding out the instrumentation were bassist Bill Wyman and drummer Charlie Watts, though all members contributed on a variety of instruments. As with most albums of the period, frequent collaborator Nicky Hopkins played piano on many of the tracks.