Size classes can be discerned in field size frequency data for Acanthaster planci which may be interpreted as age classes. This interpretation enables a possible field growth curve to be derived, which is consistent with measured growth data from the laboratory (Yamaguchi, 1974) and from field experiments by Pearson & Endean (1969). The aging of size classes enables measured size frequency data for A. planci on the Great Barrier Reef between 1966 and 1976 to be discussed as a recruitment history of the starfish. A. planci populations on all reefs for which size frequency data are available appear to have increased as a result of larval recruitment, rather than through adult migration. There appear to have been three main waves of recruitment, each affecting a section of reef spanning one to two degrees of latitude. The parental stock of the originally observed large populations of A. planci on the Great Barrier Reef was probably located north of 16° 30′ S. © 1977.