Interviewers' questioning behavior and predictive validity of applicant ratings varies considerably in unstructured interviews. A model hypothesizing a relationship between these variables is tested in this study. The model proposes that the relationship between interviewer questioning behavior and evaluation validity is mediated by the diagnosticity of applicant information that is collected during the interview. The process and content of three interviewers' questioning of 149 candidates for an entry-level correctional officer position was examined. Although the complete information gathering model was not supported, a robust relationship between questioning behavior and information diagnosticity emerged. Furthermore, the validity of individual interviewers' applicant evaluations varied considerably. These results reinforce the existence of differences in interviewers' questioning behavior and differences in the quality of applicant information they gather. Because differences in questioning behavior correspond to differences in the predictive validity of applicant ratings, both these variables should be monitored at the individual interviewer level.