This chapter presents corpus contributions to the study of input in SLA. Viewing input as the language to which learners are exposed, researchers use target language corpora as models of potential input, e.g. to map how linguistic phenomena are distributed. This can be compared to learner corpora to study input-output correlations and to assess learner needs. Researchers also use interactive corpus data to investigate input effects on learner production. Core topics such as input frequency, saliency and the reliability of form-function mappings are discussed, as are methods for researching input characteristics, learner trajectories and input effects in interaction through syntactic priming.