This document describes a process for testing the comprehension of symbols or icons. Although the process may be used to test any symbols or icons, it has been developed specifically for testing ITS active safety symbols or icons (e.g., collision avoidance), or other symbols or icons that reflect some in-vehicle ITS message or function (e.g., navigation, motorist services, infotainment). Within the process, well-defined criteria are used to identify the extent to which the perceived meaning matches the intended meaning for a representative sample of drivers. Though the process described below reflects a paper-and-pencil approach to conducting the testing, electronic means (i.e., conducted using a computer) can be used as well. The data or results from this process are analyzed to assess the drivers' comprehension of the symbol or icon. These data will be used to provide guidance in the design of in-vehicle symbols or icons.