* University Policy: Each university has its own policies regarding undergraduate enrollment in graduate courses. Some universities readily allow it, while others have stricter limitations. You'll need to check with your university's registrar's office or the graduate program you're interested in.
* Permission: Even if the university allows it, you'll usually need permission from the instructor of the graduate course and sometimes the graduate program director. This is especially true for courses with limited enrollment or those requiring a specific level of prior knowledge.
* Prerequisites: Undergraduates might need to meet the prerequisites for the graduate course, which can be more stringent than undergraduate prerequisites. The professor may require demonstration of sufficient background knowledge.
* Grading: Grades received in graduate courses taken as an undergraduate might or might not count toward the undergraduate GPA. The university's policy will dictate this. Also, sometimes the grade is recorded differently (e.g., Pass/Fail) rather than a letter grade.
* Tuition: Graduate courses typically cost more per credit hour than undergraduate courses. You'll want to understand the financial implications before enrolling.
In short, while it *is* possible, it requires proactive steps, including contacting the relevant departments and potentially obtaining necessary approvals. Don't assume you can simply register for a graduate course; plan ahead and check your university's specific policies.