The purpose of this research was to discover the effectiveness of using flashcards in improving students? vocabulary for the fourth grade of Elementary School. The writer used an experimental method. The population of this research was the students of SDN Pulau Tidung 02 Pagi, DKI Jakarta. The samples were taken from the fourth grade. The writer took 20 students for the samples in the class. The data that the writer got from the research was using the t-test formula. The result of this research showed that using flashcards in teaching and learning vocabulary is effective in increasing students? vocabulary. The tobserved = 11.93 and ttable = 1.729 . Because to>tt , it means that there is a significant improvement in teaching vocabulary through flashcards. The result was hoped to be useful for the students to help them to improve their English vocabulary. In addition, it gave information to the teachers to know the models of teaching vocabulary through flashcards in order to make the teaching and learning activities better and more effective.