The effectiveness of the cognitive interview (CI) technique has been demonstrated in experimental studies of eyewitness memory conducted in the USA, Germany, and the UK. Much of the research, however, has used college students as interviewers rather than professionals who regularly interview witnesses (e.g. police officers). The aim of this research was to examine the effects of such CI training using experienced police officers with established interviewing styles. An armed robbery was staged and information was elicited in witness interviews. The CI did not significantly increase correct recall but tended to produce more suppositions and errors. A qualitative analysis of interviewer behaviour showed that many officers had difficulty in applying the new cognitive techniques and in avoiding the use of closed and leading questions. The paper addresses two issues: first, that of training experienced police officers who have received relatively little prior training in investigative interviewing, and second, the extent to which we can generalize from the laboratory data elicited in previous studies of CI.