The diffusion of computers and their use in all linguistic disciplines, as well as the spread of the Internet, together constitute an authentic instrumental revolution in linguistics, with corpus linguistics perhaps being the clearest example here. Moreover, the teaching of languages has undergone major changes in light of technological advances, and these have affected its 75theoretical bases, its methodologies, the objectives pursued and the research derived from it. Learner corpora lie at the center of this conceptual field in which these two tendencies are closely intertwined, and which lead to them having specific characteristics, ones that will need to be identified and investigated further. These corpora gather oral and written productions of students with different L1s and at different language learning stages. In this chapter we look in depth at the study of the features of the interlanguages of each of the groups represented in the corpus (different L1s and levels); secondly, we use this knowledge to better identify possible areas of difficulty and to design the appropriate strategies for their best solution. Thus, we will review the existing Spanish learner corpora with special focus on the CAES project. This will serve as the basis for an illustration with real examples of its potential use for the teaching of Spanish as a L2, as well as research related to this. The final section will then include suggestions for further work and new developments in Spanish learner corpora studies, together with some brief comments on the application of these learner corpora for the production of teaching materials, curriculum and course design, teacher training and test design and evaluation.