The purpose of this guide is to display photographs of individual monkeys from our study groups as an aid for identification of individuals. Although detailed drawings can be useful, they may be less reliable for identification after longer periods away from the site (depending on individual drawing skills). Portrait shots can be particularly important for keeping track of growing juveniles, whose other features (like tails) can change a lot over time. Certain features of the face, however, tend to change less and can thus be used to recognize individuals more reliably. In fact, relying on facial features is probably the fastest and most reliable way to identify individual monkeys under changing conditions of light, visibility, and angle of view. Unfortunately, untrained observers usually require a very long time to recognize differences in facial expressions. Having images available for comparison may be a useful aid when learning to differentiate monkey faces, or in the very least be a fun thing to look at :-)