Developing mathematics proficiency requires an understanding of mathematics vocabulary. Although previous research has developed several measures of mathematics vocabulary at different grade levels, no study focused solely on fraction vocabularies. We developed and tested a measure of fraction vocabulary for students in Grade 4 to determine the internal consistency and difficulty level of such a measure. Analysis indicated the measure demonstrated high internal consistency. Students, on average, answered less than one-third of fraction vocabularies correctly. We also detected performance differences between students with and without mathematics difficulty and dual-language learners and their peers.