Successful use of ICT requires domain knowledge and interaction knowledge. It shapes and is shaped by the use of ICT and is less common among older adults. This paper focus on the validation of the computer literacy scale (CLS) introduced by [14]. The CLS is an objective knowledge test of ICT-related symbols and terms commonly used in the graphical user interface of interactive computer technology. It has been designed specifically for older adults with little computer knowledge and is based on the idea that knowing common symbols and terms is as necessary for using computers, as it is for reading and writing letters and books. In this paper the Computer literacy scale is described and compared with related measures for example computer expertise (CE), Computer Proficiency (CPQ) and computer anxiety (CATS). In addition criterion validity is described with predictions of successful ICT use exemplified with (1) the use of different data entry methods and (2) the use of different ticket vending machine (TVM) designs.