so im really passionate about music and ive been learning on my own time about music theory in general a lot, and i really want to take the class, but its only offered every other year at my school due to a lack of interest and it just happened to fall on my junior year instead of my senior year, where i have no time to take it within my schedule (my parents wont let me drop my language class). however, i would have time senior year to give myself an extra study hall and self teach, but ive been reading about it a lot and a lot of people seem to think its really arrogant, and that it negatively effects college applications overall. i still have a few months before i need to decide, but im not sure what to do about it because a lot of the advice already online says to only self study if it isnt offered - which is only half true for this particular class.
I wouldn’t say that. I would say that having a rigorous course load and impactful EC’s are more important for college applications, and I wouldn’t advise self studying (which will - in most cases - add zero to your application particularly when there are no corresponding scores) if that takes time from things that are more important.
Personally, I’d just take it in college
If you are looking for a moderately competitive school, you want three years of language. So they are smart. Music theory is not going to be considered a core class.
If you want credit, take the self study. But you don’t need to - and you can re-take the class again in college. It’s not going to do anything for you admission wise - it’s just a question of college credit or not.
Personally, I wouldn’t add to your work load for a lack of an admission benefit. But if it really interests you, there’s no harm.
I wouldn’t take the AP exam. Whether you self-study AP music theory just for the fun of it is up to you.
One daughter took AP music theory. She was very good at math and was a very talented musician. She found it to be a tough class, but did well in the class. She benefited from having a very good teacher for the class. I do not think that she would have done as well if she had just self-studied it. I also do not think that having taken the class had any impact on her university admissions nor on how she did when she was in university (she ended up studying something else in university).
Senior year will be busy. You will be sending in university applications. You are likely to be visiting schools. You will get results back and need to think about where you want to go. There can be a lot of effort put into these tasks that are in addition to whatever class work you have. If you are just self-studying AP music on your own time with no intention to take the exam, then when you get overwhelmed by everything else you can just postpone whatever you were thinking of doing with music.
There will be time for music at some point in the future. Plenty of people get back to it whenever their various academic requirements become less intense.
Also, quite a few universities have some music classes, and often very good music classes and very good music programs. I for example did take a couple of music classes when I was in university as a math major. Math and music are skills and interests that do sometimes coexist in the same person.
This is wise. Quite a few universities prefer students to have multiple years of language classes in high school.
Could you take it online through something like UC Scout? That way you’ve taken the class properly and not self-studied. Does your school allow for something like that if they’re not offering it that year?
Prioritizing foreign language is a good choice.
Self studying AP music theory won’t help or hurt your application, only do it if you want to do it. I will add that AP music theory is a difficult, rigorous class for many who take it. If you want to do this you can, but if at any point it is taking time away from your other courses or ECs or spending time with friends, stop. I agree with the others who have recommended taking the class in college.
Have you also talked with your high school counselor about self studying? It doesn’t sound like you would be able to take the AP test at your high school since they aren’t offering the class. Which means you will have to find another school where you could take the AP test, and that is typically difficult (and also true if you take the actual class thru an online purveyor like UC Scout.)
This is very school dependent, but I agree, OP should talk to her school about the ease of taking a test that her school doesn’t offer a class for. At my kids’ school, there are many self-study students for classes they do not offer, so there’s an option on the AP test sign up form to take literally any test AP offers, whether the school offers the class or not. My S25 self studied for the AP Physics C exams, for example, because our school doesn’t offer calculus based physics.
I agree with everyone else that there isn’t a lot of point in self studying if it isn’t for the purpose of gaining a music theory credit. If you are mainly interested in learning the material, I would just wait and take a music theory class in college, or find an online class that interests you (AP or not).
I think the general consensus here on CC is that self study has limited utility. My S25 did it for physics because one of his top two schools would have required 2 semesters of calculus based physics even though it is not particularly related to his major, and he wasn’t eager to take it. As it turned out he did not choose the school where this was the case, and dropped taking one of the two exams at the last minute. At the school he ended up at, physics isn’t required for his major and the credit essentially became elective credit.
Music theory is a very hard class, especially if you have no experience with ear training. If you are interested in this as a topic or want to be ahead for college, there are online music theory classes, one from Julliard is given over the summer. Also, most schools have a placement test for music theory since many kids will not have AP music theory but will have many years of study as part of precollege music programs.
I know your question is about AP music theory as a class/curriculum, but another great way to learn theory is by taking piano or guitar lessons. Maybe you already play one of these instruments.
Just a thought from another music lover. 
Ya beat me to it. I would learn it now more as a hobby. I am sure there are online webinars, courses, etc online and do it when you have time. Talk to your music teacher at school for suggestions.