This thesis presents the findings of a study concerning the usage of temporal prepositions conducted among Croatian speakers of the English language, students of English Language (and Literature) and students of other departments and faculties. Prepositions are a word class which denotes relations between entities. Their primary meaning is spatial, but oftentimes, metaphorical extensions of the meaning are derived from the primary one. Prepositions present a challenge to students and teachers of the English language, mostly because speakers of different languages have different perceptions of the world around them, and because L1 often influences the usage of prepositions. The test that was administered to the participants of the study consisted of two tasks, a translation task and a gap-filling task. The translation task consisted of 21 sentences, 6 experimental and 15 control sentences in Croatian. The gap-filling task consisted of 30 items, 11 experimental and 19 control items. The test was administered using Google Forms. The total number of participants was 91, 39 students of English Language (and Literature) and 52 students of other departments and faculties. The aims were determining the frequency of errors in the usage of prepositions, determining the type of errors, possible reasons behind them and comparing the two groups of students. Results showed that participants made 15.58% of errors in the usage of prepositions in both tasks, while students of English language made a statistically significantly smaller number of errors than students of other departments and faculties. Substitution was the most common error type in both tasks in both groups. Errors in both groups of students were made due to L1 influence, overgeneralization of the rules or insufficient knowledge of the rules. Students of English Language (and Literature) made no errors in several items in both tasks, while students of other faculties and departments made errors in every item of both tasks. However, errors and types of errors were similar among participants in both groups.