This chapter explores three broad principles of user-centered design methodologies: participatory design, iteration, and usability considerations. The authors highlight the importance of considering teachers as a prominent type of ITS end user, by describing the barriers teachers face as users and their role in educational technology design. To exemplify these points, they draw upon their experiences in developing the Writing Pal--an ITS for writing strategy instruction. The chapter concludes by offering a design approach--the Design Implementation Framework (DIF)--that builds upon existing cyclical design methods but is tailored to the design of ITSs and other educational technologies. [This article was published in: R. D. Roscoe, S. D. Craig, & I. Douglas (Eds). "End-user considerations in educational technology design" (pp. 76-98). Hershey, PA: IGI Global.]