Learner corpora, comprising written and/or spoken data produced by second language learners, have become an indispensable resource in language acquisition research since the 1980s. In contrast to elicited experimental data, they provide authentic evidence of learners’ actual language use, thereby yielding crucial insights into the difficulties encountered during the acquisition process. Despite the recognized value of learner corpora, resources for Persian remain limited, particularly with respect to spoken learner corpora. Moreover, while interest in the learning and teaching of colloquial Persian has been on the rise, relatively little scholarly attention has been devoted to learners’ phonological and phonetic challenges in this variety. Addressing these lacunae, this chapter first introduces corpus linguistics and the principal analytical tools available to researchers. It then surveys learner corpus-based studies with a focus on phonological and phonetic properties of learner language. Drawing on the author’s experience in compiling and analyzing a spoken learner corpus of colloquial Persian, the chapter discusses the methodological obstacles and challenges specific to the Persian context. It concludes by offering a set of considerations and recommendations, with particular attention to transcription practices, intended to guide future learner corpus-based research on spoken Persian.