In this paper, we discuss the activity systems of students and instructors who used an interactive e-textbook in their instructional activities. Data included instructor interviews and student journals about e-textbook use in eight university courses. Exploration of the data through a cultural-historical activity theory lens indicated that e-textbook use can be limited when students act on it merely as an object without any intentional goal. Without requirements by the instructor, the embedded tools in the e-textbook may do little to support the student activity in the system. In addition, many instructors, as well, approached the e-textbook as an object, and a number of them did not include the e-textbook in their own activity systems. Considering the e-textbook as a mediating tool to address other goals (such as completing an assignment) or to support instructional decisions by faculty through developed awareness of students' understandings, positioned the e-textbook as a mediator of learning, rather than an object on which to act. We end our discussion pointing to the need for an expansive transformation regarding the use of e-textbooks so they may be positioned as new kinds of mediating tools for learning.