This paper presents an investigation of the association between similarity of interests and likability in a manner as nearly comparable as possible to earlier attitude and personality research. The finding of a strong, positive relationship between similarity of interests and likability would be significant for two reasons. First, it would represent an extension of the similarity-attraction hypothesis, so important in personality research, to the field of vocational behavior. Second, positive findings would provide further support for Halland's theory of vocational choice by testing the validity of some of its assumptions. When results were compared directly with previous research concerning the effects of similarity of attitudes or personality on likability, a strong positive relationship was found between interest similarity and rated attraction. The implications of these findings for a major theory of vocational behavior are discussed. (Author)