The Computer Aided Learning (CAL) working group of the SOCRATES thematic network in Speech Communication Science have studied how the Internet is being used and could be used for the provision of self-study materials for education. In this paper we follow up previous recommendations for the design of Internet tutorials with recommendations for their evaluation. The paper proposes that evaluation should be seen as a necessary quality assurance mechanism operating within the life-cycle of CAL materials development. We propose a structured set of criteria for evaluation, based on the features of good tutorials, against which a tutorial might be judged. Since evaluation against fixed criteria is only one possible approach, we outline how evaluation could also be performed by student users and in controlled trials.