Knowing a foreign language has become crucial to reach information. Learning vocabulary is the fundamental step to learn a foreign language. New devices are invented everyday to fulfill the needs of citizens of the twenty-first century. Increased use of mobile phones has made them popular for not only communication, but also entertainment and learning purposes. Mobile phones have provided remarkable advantages in learning process. They provide opportunity for learning to occur outside the classroom walls in anytime and anyplace. The effects of using vocabulary learning programs in mobile phones on students' English vocabulary learning are investigated using the mixed-method research design with sixty students studying in the Undergraduate Compulsory Preparatory Program of a public university located in the Black Sea region of Turkey. Results indicated that using mobile phones as a vocabulary learning tool is more effective than one of the traditional vocabulary learning tools. (Contains 1 figure and 4 tables.)