The goal of this chapter is to outline a theoretical and empirical perspective on how learners' conceptions of educational technology might influence their learning activities and thereby determine the power of computer-based learning environments. Starting with an introduction to the concept of powerful learning environments we outline how recent developments in information and communication technologies might be used to implement these environments technologically. In the next step we refer to several exemplary empirical studies to argue that the power of computer-based learning environments will largely depend on very detailed aspects of the learning activities within these environments. In order to design these environments so that they elicit effective learning activities, it is necessary to analyze the factors that determine learners' goals and their choices of processing strategies. The focus of this paper is on one of these factors, namely on learners' instructional conceptions with regard to educational technology and its use in instruction. Up to now, there has been nearly no research conducted within the educational community addressing the issue of how this particular type of instructional conceptions determine learning activities. Therefore, we review several relevant findings from neighboring fields like epistemological beliefs, attitude research, human computer interaction, or cognitive modeling. We use this review to demonstrate that there are numerous findings outside the educational technology community that deserve much more resonance in this community than they currently receive.