This study explored evidence of the construct validity of the interest scales on the Campbell Interest and Skill Survey (CISS; Campbell, Hyne, & Nilsen, 1992) by testing evidence for convergent validity with the Strong Interest Inventory (SII; Hansen & Campbell, 1985). Two hypotheses were formulated. First, matching CISS and SII scales were expected to be more positively correlated compared to non-matching scales. Second, Holland's hexagonal calculus assumption (Holland, 1973) was expected to emerge in the pattern of intercorrelations among CISS and SII scales. These hypotheses were tested using correlational and factor analyses. Results supported the hypotheses and demonstrated evidence of good convergent and construct validity for scores on the CISS interest scales. Implications for the use of the CISS in counseling and for research on Holland's theory are discussed, and directions for future research are presented.