Observers' deception detection accuracy tends to differ depending on the speakers' language proficiencies (e.g., Elliot & Leach, 2016). We explored whether rapport was an underlying factor. Participants with different language proficiencies (i.e., beginner, intermediate, advanced or native English) were instructed to lie or tell the truth during an interview. Then, they completed rapport questionnaires. We hypothesized that rapport would be higher for truth-tellers than lie-tellers. However, we expected that this effect would be exacerbated when language proficiency was poorest (i.e., the lowest rapport would be reported by deceptive beginner English speakers vs. all other groups).