Academic writing is a complex task that involves a variety of cognitive and metacognitive activities. One approach to assist writers in dealing with the problem of managing their resources during writing is to scaffold writing by computer. Unfortunately, empirical research on computer-based scaffolding (CBS) of writing is quite limited, and the results are mixed. An explanation for these results may be found in the design of the scaffolding. Most CBS support discrete writing activities, independently from the writing process. This chapter seeks to contribute to the question of how to design CBS which supports the academic writing process as a whole. As a basis for the design, the subtask model of academic writing is presented which explicitly describes the demands of academic writing. This model is derived from theoretical and empirical findings on expert writing. The implementation of CBS for expert writing activities into the writing environment escribo is then described. The CBS stepwise supports the application of these expert writing activities. To this end, escribo decomposes the writing process in its subtasks and provides specific instruction and tools for the completion of each activity. Furthermore, two evaluation studies on the effects of the writing environment are summarized. The results show that working with escribo is superior to a situation without CBS. Implications of these results will be discussed with regard to the benefits and restrictions of fostering expert writing activities through computer-based scaffolding.