A pronoun shift is a type of grammatical error created when an author begins a sentence or paragraph using one pronoun and then switches, in the middle of that sentence or paragraph, to a different pronoun. A pronoun, by definition, is a noun that can function by itself and that refers either to participants in a conversation, like I or you, or to someone or something already mentioned elsewhere in the conversation. An example of the latter would be if two people were having a conversation about a person named Mary and Mary had already been named; the two people could now refer to Mary as she and still understand whom they are talking about.

An example of a pronoun shift would be a sentence that reads, "I wondered how many times I would feel this way because you just never know how happy or unhappy your life will be." In the midst of this sentence, I switch my pronoun usage from I to you, and this constitutes a pronoun shift. It would be better to say, "I wondered how many times I would feel this way because I cannot know how happy or unhappy my life will be." Another example might read, "When my grandmother was in school, she says you were taught to be polite." At first, I am referring to my grandmother in the third-person, but then I shift to a second-person pronoun for no good reason. It would be better to say, "When my grandmother was in school, she says that she was taught to be polite."