Individual differences are prevalent in personal information management (PIM). There is large variation between individuals in how they structure and retrieve information from personal archives. These differences make it hard to develop general PIM tools. However we know little about the origins of these differences. We present two studies evaluating whether differences arise from personality traits, by exploring whether different personalities structure personal archives differently. The first exploratory study asks participants to identify PIM cues that signal personality traits. While the aim was to identify cues, these cues also proved surprisingly accurate indicators of personality. In a second study, to evaluate these cues, we directly measure relations between structure and traits. We demonstrate that Conscientiousness predicts file organization, particularly PC users' desktops. Neurotic people may also keep more desktop files. One implication is that systems might be customized for different personalities. We also advance personality theory, showing that personal digital artifacts signal personality.