Technological advances have made possible a new generation of digital prosthetic memory devices (or memory aids). Yet we currently know little about when, how and why these devices might be useful. We evaluated two novel prosthetic memory devices in naturalistic and controlled learning settings. Both devices provide controlled access to annotated digital records of lectures, potentially freeing students from taking detailed notes, allowing them to re-access lecture recordings whenever they choose. Digital records had benefits over traditional learning aids (e.g. handouts/personal notes): Students were more accurate in answering class quizzes using digital records, and spontaneous digital records usage outside lectures showed strategic access during important aspects of the course. Native speakers who used digital records performed better on coursework, and non-native language speakers used digital records extensively. Despite being a verbatim record, digital records did not substitute for attendance: students who had attended lectures performed better on quizzes and final coursework and few students listened to lectures from beginning to end. Digital records are thus a highly promising teaching tool, but prosthetic memory devices are best understood as working in synergy with current tools to aid human memory, rather than replacing it. We conclude by discussing potential theory and design implications. © 2010 Elsevier Ltd. All rights reserved.