This study examined the construct validity of the Rod and Frame Test (RFT). Subjects were 554 clients (269 males and 285 females) (aged 14 to 65 years) of the Johnson O'Connor Research Foundation (JOCRF), a vocational guidance service. In a battery of diverse ability and style tests (19 tests of the JOCRF battery and 4 tests of cognitive style), the RFT's highest correlations were with spatial visualization. Also, in a principal components analysis, the RFT loaded 0.59 on a spatial ability factor and did not load on any other factors. A multiple regression of the RFT on the cognitive ability tests, however, yielded a multiple correlation of only 0.35. It is concluded that the RFT measures a type of visuospatial ability that is related to other spatial abilities, but is also, to a considerable extent, unique to itself. There is some evidence that the RFT may be more strongly related to spatial visualization among men than among women. A table lists correlations between the RFT and the other ability and style tests. A 10-item list of references is included. (Author/SLD)