<p>I doubt it’s “common,” but it’s not restricted. You may have a bias against you in committee, and if you’re applying in a humanities discipline you might have more trouble (schools, often unlike science/math/etc., strongly encourage you to go somewhere else for your graduate degree), but…</p>
<p>I know of at least one student in the English department who went to Cal as an undergrad. I also know a math major who is now a grad student at Cal.</p>
<p>So it HAPPENS, but remember that Cal is the top grad program in a lot of fields, and they don’t want to glut with their own students, so I wouldn’t call it “common.”</p>