Possessive pronouns are used to clarify whether something belongs to the speaking, conversational or non-speaking person and are defined according to persons. In the part of the paper where the theory is discussed, attention is firstly devoted to the types of words from which everything starts, then to pronouns in general, and finally to possessive pronouns and their declension. The second part of the paper is based on the conducted research on possessive pronouns. The questionnaire was answered by 106 respondents, and the collected answers were broken down with regard to the level of education and the native dialect. The questionnaire contained two types of tasks and each task consisted of ten sentences. At the end, the results of all respondents were presented, and it became clear which task the respondents solved better, and which examples were a problem for them. The goal of the research was to judge whether the respondents know the norm of the Croatian standard language and whether they use it. The purpose of the research was to see the most common errors of respondents when using possessive pronouns. The results of the research showed that the respondents were more successful in the second task, in which they chose one of the two offered answers, than in the first task, in which they themselves had to complete the required form of the possessive pronoun. Although they were more successful in the second task, the overall results of the research are devastating and prove that very few respondents know the norm of the Croatian standard language. Therefore, when designing the curriculum, one should take into account the representation of language content not only at the reception level, but also at the production level, and increase the number of hours devoted to written expression.