The questionnaire developed for this study was based on previous research, both laboratory-based studies and studies with higher ecological validity, that focused on various aspects of deception. The seven items central to the questionnaire were details provided, gaze behavior, consistency of consecutive statements, body movements, voice pitch, whether interrogators or observers are more accurate in determining deception, and whether verbal or nonverbal cues are more reliable in detecting deception. For each item, the respondents were asked to provide their opinion on forced-choice answer scales regarding the importance of the item in detecting deception. The sample consisted of 104 police officers (38 women and 64 men), 158 prosecutors (61 women and 97 men), and 261 judges (59 women and 190 men). The findings indicate that all of the criminal justice professions represented held beliefs about the detection of deception that are inconsistent with the findings of studies that have examined the actual cues that are most reliable in detecting deception (Vrij, 2000). The majority of police officers subscribed to the belief that liars are more gaze aversive than truth-tellers; however, the research literature shows that there is no relationship between gaze aversion and deception. Although all the professional groups represented strongly believed that deceptive consecutive statements are less consistent than truthful consecutive statements, previous research has found that deceptive statements are at least equally consistent compared with truthful statements. The majority of police officers believed that there is an increase in body movements during deception, but research has shown that liars often have less body movement than truth-tellers. Although all three groups believed that interrogators are more accurate in detecting deception than those who observe interviews on videotape, research has shown the opposite. For all professional groups, a large number believed that verbal and nonverbal cues to deception are equally reliable, with some variations on emphasis among the three groups. Research shows the those who focus on verbal cues tend to achieve higher accuracy scores than those who are more trusting of nonverbal cues. There were disagreements about the priority to be given the various factors between and within the professional groups. Generally, however, the beliefs of the three groups about the detection of deception fit poorly with the findings of the scientific literature. Given the influence that such beliefs have on the investigation, processing, and outcomes of cases, it is important that researchers in the field of deception disseminate their findings to those professions whose beliefs and decisions in this field can have such an impact on the lives of those processed by the criminal justice system. 2 tables, 7 figures, and 33 references