With this study, first-grade students studying in the department of English Language Teaching were consulted for their opinions related to vocabulary teaching through word-formation. For this purpose, data were collected using the semi-structured interview form technique. The results obtained in the light of these data showed that this applied vocabulary learning method contributed to improving the vocabulary of the pre-service English teachers who participated in the study in general. In this context, it was seen that while reading an English text or listening to English with the help of prefixes and suffixes they learned, they could guess the meaning of the unknown word by dividing the word into its suffix and root. In this respect, it can be stated that students have improved their receptive vocabulary knowledge. On the other hand, it can be concluded that students have developed their own productive vocabulary by deriving new words through the prefixes and suffixes they have learned. Based on the students’ opinions, in addition to prefixes and suffixes, it is understood that students also have learned new words through compound word-formation. Finally, it can be said that vocabulary teaching based on word formation creates awareness among students about word types..