By questionnaire, 631 police investigators reported on their interrogation beliefs and practices—the first such survey ever conducted. Overall, participants estimated that they were 77% accurate at truth and lie detection, that 81% of suspects waive Miranda rights, that the mean length of interrogation is 1.6 hours, and that they elicit self-incriminating statements from 68% of suspects, 4.78% from innocents. Overall, 81% felt that interrogations should be recorded. As for self-reported usage of various interrogation tactics, the most common were to physically isolate suspects, identify contradictions in suspects' accounts, establish rapport, confront suspects with evidence of their guilt, and appeal to self-interests. Results were discussed for their consistency with prior research, policy implications, and methodological shortcomings.