This paper discusses how Holland's formulation of his hexagonal model to re
present the structure of interests has influenced the development, validati
on, and application of interest inventories, especially the Strong-Campbell
Interest Inventory (SCII), the Campbell Interest and Skill Survey (CISS),
and the Strong Interest Inventory (SII). Holland's theory was especially po
tent in stimulating the major, and lasting, innovations Campbell (1974) cre
ated in the SCII: (1) The introduction of two kinds of content scales, the
broad Holland scales and the more specific Basic Interest Scales; (2) the c
omplete reorganization of the inventory within the hexagonal system; and (3
) the building of a merged inventory for men and women. (C) 1999 Academic P
ress.