Contrastive linguistics has traditionally been referential for the analysis and the comparison of languages in order to identify linguistic patterns, which may later enable linguists to validate the norms that they propose to understand language. This analysis started from some psychological assumptions in the arena of behaviorism leading to some methodological principles 90for the study of communication in societies. The expected scenario was, however, linguistic, as languages are the focus of study. One obvious methodological approach in contrastive linguistics is through the use of parallel corpora, as this is a very objective way to analyze and excerpt data when dealing with linguistic phenomena in bilingual and multilingual settings. Parallel corpora help us to identify recurrent patterns in a language in addition to detect variation emerging as a result of particular language use, both from a diachronic and synchronic perspective. The use of this type of corpora is especially convenient to evaluate the interpretation of variables in the source languages, and the subsequent choices that translators make to render specific language phenomena in the target languages, no matter how idiosyncratic these may be. Linguists have found a wealth of information in these language selections for the categorization of grammatical units. Taking everything into account, the objectives of this chapter will be, first of all, (a) to identify the main studies performed within the field of contrastive linguistics; secondly, (b) to describe the most relevant studies based on parallel bodies of data; third, (c) to classify the different types of parallel corpora available to linguists and, finally, (d) to offer one example of research carried out on a parallel corpus (Spanish and English) with a focus on the comparison of discursive markers in these languages. This chapter is expected to offer information pertaining the characteristics of parallel corpora and their classification along with a case study serving as an illustration of the benefits these corpora may bring for linguistic enquiry and language learning.