In its publications, the MLA generally does not use the plural pronoun they (or their, them, and themselves) to refer to singular nouns. While the singular they is not uncommon in spoken English and in some informal contexts, in formal writing it is best to reword for agreement in number. In the following example their and they are mismatched with each student:
Each student is expected to choose the topic of their research paper before they take the midterm.
In our editorial practice,
Published 3 October 2018