Hello.
Is it possible to study first undergraduate studies and then graduate studies and then PhD, all at Harvard?
Yes, if you are brilliant.
For some majors, it is not really done. For instance, an undergrad music major is not going to do grad work at Harvard, at least without something else in between. I don’t know how this works for various majors but generally speaking I think it might be unusual to go right into grad work at Harvard after undergrad. If this is relevant to your life I would call and ask.
There is a general bias against going directly from a undergraduate degree right into the graduate program at the same school. Exceptions are made, but not too often. The rate of exceptions varies by school and program.
It’s relatively common to get both an undergraduate degree and a professional degree (MD, JD, MBA, MPP, EdD) from the same university. I would bet that Harvard College is the #1 undergraduate institution for students at Harvard Law School or Harvard Business School, although they probably constitute only 10-15% of the professional-school class. With PhD programs, however, it’s unusual, and there’s something of a taboo against it. People talk about getting perspectives from more than one department, but I think the real reason is to protect faculty from students they may have to (and want to) deal with every day, as students, research assistants, advisees, etc. It’s a lot easier to say, “I think you’re great, but we have a policy against taking our own undergraduates,” than it is to say, “I’m happy to give you a good recommendation, but we can get someone better than you from the application pile.”
The OP is debating between enrolling in Harvard College versus Harvard Extension School on another thread so this discussion is purely theoretical.
JHS what about undergrads who go elsewhere for a master’s and then want to return for PhD? Just curious. I have always wondered about this. It is now relevant to someone I know…
@compmom, this is anecdotal but somewhat answers your question. A friend did his BA at H, his MA at BU, and then returned to H for his PhD. I do not know if the external master’s helped or not. I do know that a faculty connection made during undergrad was helpful. @JHS is right about the taboo. It can also keep a university from hiring its own PhDs as faculty. The extent to which this “inbreeding” is avoided by universities has been debated here. There is no question that it is a concern of many departments. Best wishes.
I have seen more PhD’s hired than undergrads doing grad work 
But my experience is very very limited. Thanks!!
^^^ Sorry if I was unclear; I was referring to PhDs being hired as tenure track permanent faculty, not as grad assistants, which is the norm.
No, I understood. Thanks.
With respect to PhD programs, the preference or anti-preference for students who graduated from the same school’s undergraduate program is highly variable across disciplines and schools.
I was an undergrad at Harvard, and got into the PhD program at Harvard, but my advisors all recommended that it would be good for me to go someplace else… so I opted for Berkeley (over Harvard, MIT, Caltech, Columbia, Chicago). The vast majority of folks I know who got PhDs in science disciplines went to different schools for their graduate degrees.
On the other hand, anecdotally, I observe that it is not uncommon for students who attend a major flagship public institution to stay at the same flagship public for a PhD. I have heard from friends (again anecdotally) that MIT is one of the few private research institutions that seems to have a slight preference, or at least no anti-preference, for their own undergrads.