While police considered themselves only slightly less informed about eyewitness issues than did lawyers, and students and psychologists considered themselves least well-informed; police showed the poorest performance of all groups in their actual knowledge. No clear relationships were found between the groups' levels of confidence in their answers and their levels of accuracy. Respondents generally were aware of the effects of stress and anxiety on memory, but were less aware of the effects of violent versus nonviolent crime on perception and recall. Police were more likely to be aware of these effects than were other groups, but were less aware of the effects of question wording and format. Compared to other groups, police also had the lowest level of correct responses to questions on cross-racial identification. They were also more likely than other groups to believe that police officers make better eyewitnesses than others. While police had a high percentage of correct responses regarding elderly eyewitnesses, they showed the poorest performance regarding child witnesses. All groups showed poor awareness of voice identification issues. Implications for police practices are discussed. 2 tables and 44 references.