This paper describes our work in developing the human-computer interface of an augmented reality (AR) system designed to facilitate the accurate selection of real world locations in 3D space using 3D cursors. The results of two experiments undertaken to evaluate the influence of certain sources of additional depth information and degree of interface control are presented. The merits of stereoscopic displays and various cursor designs are also investigated. Results indicate that the benefits of stereoscopic displays do not significantly outweigh the benefits offered by increased control and additional positional information when performing simple object selection tasks in unprepared AR environments.