To make certain that you have a clear sense of how you want to proceed once you've completed your undergraduate work in Sociology check into the appropriate prepartion work now. Talk to professors about graduate school possibilities. There are excellent pre-graduate advising services available through the Advising Services Office. You can also investigate various graduate programs on your own.
Sociology faculty are an invaluable resource when preparing for graduate work - talk with them. Faculty are well versed in how to proceed with preparation for graduate work, they can make recommendations about which institutions to consider, and they can serve as a sounding board for your ideas and plans.
Be sure to use all your resources when considering an advanced degree program. If you need help choosing the master's program best suited to your goals, or, if you are interested in Ph.D. work, see a Sociology faculty member. You can also stop by the Internship & Career Center and see a graduate school advisor.