Research on investigative interviewing has highlighted the role of rapport in nonconfrontational, evidence-based interviewing procedures, but questions remain about the nature and function of rapport in such interviews. Across three samples drawn from multiple previous studies involving similar methodologies, we addressed four issues: a potential role of working alliance as a rapport component, differences among different sources of rapport data, interrelationships among rapport components, and cultural/ethnic moderation. Rapport was coded from videos of introductory segments of interviews concerning a mock theft involving interviewees of different cultures/ethnicities. The rapport components were intercorrelated, converged on a single factor, and were associated with interviewer but not interviewee self-assessments of rapport. Rapport differentially predicted the informational elements interviewees produced: working alliance predicted relevant details and plausibility, but coordination predicted irrelevant details, with some culture/ethnicity moderation. We discussed these findings in relation to future theory and research on rapport in investigative interviews.