In our junior year, history majors write two juniors papers (JPs). These JPs cannot focus on the same geographic area, in order for us to get a broader exposure to the subject.
In the spring of sophomore year, new majors rank their top choices from a list of seminar topics that the department releases. The subject of the seminar will be the general topic of the JP. The department tries to create a seminar list that has a wide and interesting variety of topics, with each topic covering a large geographic area, a large time period, or both, in order to offer a wide range of possible JP topics. Over the course of the seminar, the instructor initially provides material that gives the students enough background from which to choose a good JP subject. After about mid-semester, the extent of content-related material lessens and the instructor focuses on helping students with issues encountered in the actual writing phase of the paper.
For the spring JP, each student picks a JP adviser from a list of available professors in the department. The student then must come up with a topic, begin research, and write the paper with as much guidance from the adviser as the student wants. Some want a lot of guidance; some don't. But your adviser will be the one to grade it, so you might want to listen to what he or she has to say.
Both JPs ought to be between 25 and 30 pages long, and they are intended to rely heavily on primary source material. Getting into primary sources that early and intensely helps for jumping into the thesis next year!
Students can pick their thesis adviser as soon as the professors are willing to be tied down. Some students do it before junior year ends, and some do it at the beginning of senior year. Either way, by October, you have to turn in a form stating that your adviser has agreed to advise you, otherwise the department will assign you one, trying to meet your preferences to the best of its abilities. Then, over the course of the rest of the year, the student works with the adviser to come up with an 80 to 100 page thesis, using primary and secondary sources to do in-depth, original research on a subject. There are some general recommendations for benchmarks, but specific requirements are up to the student and the adviser. The only fixed deadline is the day it's due: early April.
A professor has described the whole independent work process as like committing oneself to a long-term, very close relationship. It is a very fitting analogy; you get to know the topic almost personally, and it is a memory you take with you for the rest of your life, something that you can be proud of and that you will tell about to everyone who will listen. The thesis is definitely a time-honored rite of passage at Princeton.
The last thing to turn in is your comprehensive exam, which is taken at the end of the spring semester. The subject in which you take your comprehensive exams is technically your concentration in the department, and it doesn't have to be the same concentration as your thesis (although for most people it is). Any student can take any comprehensive exam with no course prerequisites, with the exception of American history concentrators, who must have taken two courses in pre-20th century American history. It is given over a three day period, but there are maximum page limits to each question, so you don't have to go overboard on it. They are designed to make sure that you learned at least something from the department, both in terms of subject matter and writing ability.
Being a history major is pretty fantastic. The professors are very nice and accommodating, and they are happy to talk with you during office hours, although there may be a line - there are a lot of us! The front office people are terrific, led by the Administrator Etta Recke. She makes everything work, and she is extremely kind, so knowing her is both helpful and delightful. And then the peer-elected undergraduate advisory council of history majors is supposed to make sure that all majors are happy and also to bring student concerns to the department. This council organizes study breaks and various events for department majors to come together and talk history!
All of this leads to the conclusion that the history department is pretty awesome.