This chapter begins an exploration of how computer technologies impact on the cognitive processes of individual writers. In particular, this chapter examines how reading and rereading are changed when writers use computers. In keeping with chapter 2's argument that Technology Studies should look at, rather than through, technology, the intent here is to focus on computers themselves, rather than simply on computers' effects. Consequently, several different display and presentation variables are examined, and the chapter concludes with a framework of features of computer writing systems that helps to account for the findings presented here. One of the most important findings of these studies is that a computer is not a computer is not a computer; that is, there were strikingly different results for different computer systems. These findings suggest that the computer is not an all-powerful monolith, and that computers' effects are not unitary. Rather, computers can-depending on how they are configured and how they are used-have vastly different effects on writers and writing.