Your first decision is to choose the sub-area of your discipline that you want to focus on. What really interests you? If you are a history student, is it ancient Greece or the French Revolution or modern China? If you are a biology student, is it human genetics or ecology or ornithology? This doesn't mean a vague, lukewarm interest. It means what you are passionate about. If you are going to spend up to a year studying something, you had better be really interested in it. For some students, this is an easy decision—it's the area covered by the courses you could hardly wait to get into and loved the whole way through.
Once you've settled on a general area of interest, you can start to narrow it down. What fascinates you most about the French Revolution—the peasants, the bourgeoisie, or the aristocracy? Which birds intrigue you most, and what do you want to know about them? You need to be very practical here. To take an extreme case, no matter how interested you are in studying penguins in their natural habitat, it's probably not a smart choice if you are located in Pennsylvania.
The boundaries for acceptable thesis topics vary from discipline to discipline, but some common principles apply. A thesis topic should raise a question or questions for which answers are not readily apparent. It should allow you to demonstrate your ability to use the research methods of your discipline and to tackle creatively a problem considered significant in your field. It has to be feasible given the time you have and given the library, laboratory, and field resources that are available.
Don't try to come up with one perfect, well-defined idea all by yourself. A better approach at this stage is to make a list of several ideas that seem plausible to you and then identify a professor who might be willing to direct your thesis. Once you've found a faculty member to work with, he or she will be able to help you evaluate and choose among the ideas you've generated. As an expert in the field, he or she might see possibilities and obstacles that you have missed. In some disciplines, it is even common for a professor to invite you to join a large, ongoing research project and to give you responsibility for a small part of that project as a thesis. Most good thesis topics emerge out of conversations between students and their thesis directors, just as many good topics for the smaller thesis papers you wrote in honors core courses grew out of conversations you had with your core professors.
If you are having trouble thinking of a topic, it can be useful to remind yourself that you sometimes struggled to come up with a good topic for core papers—and yet somehow, after talking with other students and the professor, it all came together in the end. Don't give up too easily or think you have to plan your thesis alone. You are expected to seek help and guidance.
Next > Finding a faculty member to direct the thesis