You may find it weird but at my school we don't wear a cap and gown. Since I go to an all-girls school, we have a lot of different traditions and we wear white dresses for 3/4 Senior ceremonies we have.
In this picture I'm wearing the cap I got before the ceremony. I just felt like looking like an actual graduate.
The next white dress I had to wear was this long embellished one. This isn't a great picture of the details, but it was beautiful. I had a great evening as well; it was basically my school's version of Prom.