Despite claims that the use of corpus tools can have a major impact in language classrooms (e.g., Conrad, 2000, 2004; Davies, 2004; O'Keefe, McCarthy, & Carter, 2007; Sinclair, 2004b; Tsui, 2004), many language teachers express apparent apathy or even resistance towards adding corpus tools to their repertoire (Cortes, 2013b). This study examines from a teacher cognition perspective (Borg, 2006) how three EAP (English for Academic Purposes) writing teachers identified their most pressing needs and considered possible ways that corpus tools might address those needs. After having an individualized corpus working session, each teacher put into practice one or more corpus tools to address self-identified needs in their writing classes. The teachers reflected on the process across a series of interviews and in a stimulated recall session, which were analyzed using qualitative research methods. Each teacher discussed the degree to which the lesson met her objectives, and considered how she might use such corpus tools in the future, as one component in the development of her teaching beliefs, knowledge base, and practices. Through thematic analysis of the interviews and the individualized corpus working sessions, themes emerged that tell the story of these three teachers as they moved through this process, relating to the issues of time, student engagement, material analysis, selection and design, issues related to corpus tools, language, institutional factors, and collaboration. A new area of specialization on the pedagogical uses of corpus tools is discussed, based on the results of the three cases. Implications for researchers, material designers, corpus tools specialists, teacher educators, administrators and teachers are considered.