In the US and the UK, many thousands of police suspects are identified by  eyewitnesses every year. Unfortunately, many of those suspects are innocent, which becomes evident when they are exonerated by DNA testing, often after having been imprisoned for years [1]. It is therefore imperative to use identification procedures that best enable eyewitnesses to discriminate innocent from guilty suspects. Although police investigators in both countries often administer lineup procedures, the details of how lineups are presented are quite different and an important direct comparison has yet to be conducted. We investigated whether these two lineup procedures differ in terms of 1) discriminability (using receiver operating characteristic analysis) and 2) reliability (using confidence-accuracy characteristic analysis). A total of 2249 participants watched a video of a crime and were later tested using either a 6- person simultaneous photo lineup procedure (US) or a 9-person sequential video lineup procedure (UK). US lineup procedure yielded significantly higher discriminability and significantly higher reliability. The results do not pinpoint the reason for the observed difference between the two procedures, but they do suggest that there is much room for improvement with the UK lineup.