This study examined how a principle of social influence--reciprocity--affects the informational elements produced in an investigative interview. Participants from 3 ethnic/cultural groups recruited from the community either received a bottle of water or not prior to their engaging in an investigative interview, in which they either told the truth or lied about having committed a mock crime. Three different informational elements (Relevant details, Irrelevant details, and Plausibility) were coded from their responses, and rapport in the interaction was coded from video. Offering water facilitated greater rapport and influenced the informational elements. These effects were moderated by Veracity condition: For liars, offering water produced more Relevant details and greater Plausibility in the statements and this effect was mediated by rapport. Ethnicity/culture did not moderate these findings. These findings suggested the applicability of principles of social influence in investigative interviews across cultures/ethnicities and had theoretical, empirical, and practical implications.