The assessment of interests through the use of interest inventories is big business in the field of testing today. Although publishers closely guard their data on the number of inventories given, an estimate of 3,000,000 administrations per year probably is conservative.
The first formal assessment of interests using a published inventory occurred in 1927 with the appearance of the Strong Vocational Interest Blank. Since that time, the Strong has survived numerous revisions and continues to be a popular and widely used interest inventory.

Interests were assessed prior to 1927 using, basically, four techniques.
The earliest of these techniques was estimation, which simply involved asking an individual to indicate her or his feelings towards an activity. Because estimates were not always accurate, individuals often were encouraged to try-out activities as another method for assessing their interests. Obviously, try-outs could be quite time-consuming and costly, and rating scales and checklists, precursors to interest inventories, were developed to identify interests more systematically. The interest inventories that we use today differ from early checklists and ratings in that they use statistical methods to summarize responses to pools of items representing various activities and occupations (Hansen, 1984).