The importance of format, graphic layout, and question routing instructions on the quality of survey data has been acknowledged for self-administered survey instruments, but the significance of these factors for questionnaires administered by interviewers has not been recognized equally. This paper examines two studies in which interviewers used different questionnaire designs to administer the same set of survey questions to randomly selected adult respondents in housing units that made up area probability samples of the Detroit metropolitan area. The paper presents empirical evidence of specific effects (questions skipped in error, unprobed answers) directly attributable to the choice of questionnaire design. The analysis shows that question naire design choices can either help or hurt the quality of data collected by interviewers. Furthermore, the behaviors of experienced and inexperienced interviewers are affected in similar ways. In other words, interviewing experience does not compensate for format deficits in the design of survey instruments.