This paper looks at pro-form and cohesion in English writing from the angle of Korean L2 writers' mental script and attempts to suggest an interpretation of their responses in pro-form substitution. In English writing, to boost cohesion repetitive key nouns are typically substituted by pro-forms only if clarity is salvaged. However, how can we explain contrastive cases where Korean L2 writers prefer repetitive nouns to remain as they are without weakening the cohesion of a text? The writers attempt to explain this unsolved question, based on the survey results from Korean L2 writers and by referring to related theories of Oshima and Hogue (2006), Hyland (2009) and Hyun (2015). So far our research indicates that such response is attributable to Korean L2 writers' own schema and then this schema issue subsequently translates into their genre difference.