Apart from the procedural information that describes how a device should be operated, instructions for use include different types of declarative information, such as information about the internal working of the device (system information) and information about the circumstances in which the different functions can be used (utilization information). In this study, the use and the effects of system and utilization information are investigated in a number of experiments. The results demonstrate that users spend a considerable amount of time on reading each information type. However, contrary to common belief, system information has only limited effects; utilization information does not affect task performance at all. Moreover, users of instructions without declarative information are more confident in their ability to learn to work with the device and consider the learning process less difficult than users of instructions with declarative information. These results suggest that users of instructions without system and utilization information are capable to use other information sources such as the procedural information and the interface of the device to derive the required declarative knowledge.