The elaboration of separation-individuation theory in the years beyond chil
dhood has been a psychoanalytic focus for several decades. In this paper, t
he nature of separation-individuation phenomena in adulthood and the termin
ology and controversy surrounding the use of the terms third, fourth, and f
ifth individuation are considered first; a detailed elaboration of the conc
ept of the fifth individuation in late adulthood follows.