Will quitting a temporary semi-professional job without notice hurt my career after college?

I was initially pretty happy about getting a new job at a graduate school as one of their admin. assistants. It was temporary, but I was making more than I ever had before. Unfortunately, I hate the job. They knit-pick with everything I do. I called in once or twice and they got on my case so bad. Meanwhile, they take more personal and sick days than any other office I have ever seen. It just seemed very hypocritical. They also refused to continue being flexible with my academic career. I am about to graduate from college in May. Recently, I have actually missed classes so that I can stay there and work, but if I miss anymore then I will have to drop my classes and not graduate until the summer. I have worked there for a little over 3 months, but I cannot take another day. Yesterday I was out sick and decided that I am just not going back. However, would it be weird to send them a letter or an explanation or something after the fact?

This is a pretty touchy situation. You never want to quit your job without notice because it doesn't look good if an employer would call for a reference, however, most employers don't care for references.

If I were you, I would quit (without notice) and send them a letter and just say something to the affect that the job is interferring with your school work and leave it at that.

If would would be questioned about this later by a future employer, explain that they job was too demanding to hold while also attending school. Say something to the affect that you had a hard semester and you felt that it would be more important to keep your grades up than to hold a job.
If they would ask why you didn't give notice you can say that you were in a sitaution that you had too many exams in one week and your schedule was too hectic to allow them a period to give notice, and make sure that you say that you feel really bad about it.

Also, make sure that this "not giving notice" thing is a one time deal. You can only make up so many excuses

Not really. Most employers who hire new graduates are only interested in their qualifications.

That would be unproffesional of you. Don't send them a letter. Walk it in. Give them official notice, inform them that they are damaging your college courses and that you can no longer take that risk, and then apologize nicely for being so abrupt and leave. Don't ask for a reference.

School must come first. You just make the great grades & a fabulous job will come your way!

Keep the letter simple. You cannot maintain your level of study and keep workign for them. They will understand that your education comes first. On average, give them 1 days notice for every month worked.

DO NOT MENTION ANY OTHER REASONS FOR LEAVING!

Chances are that they already know about their failings. Pointing it out to them is like burning your bridges behind you.

A letter AFTER you quit won't really make a difference. The damage is done. Since your in college, I assume your still young. One small blemish on your work history isn't going to destroy any future prospects. If you decide to apply at a different job, I just advise you not to put this job as a reference.

Yes, it would be wierd to send them a letter explaining why you quit without notice. Why would you do that? Are you trying to change them? It rather comes across as a "so I took my ball and WENT HOME" thing, not very professional.

I would tend to suggest going ahead and quitting formally, giving notice. It sounds from your description that they don't appreciate/like you, so it's quite possible they won't require you to stay, having given notice, that they'll just tell you not to come in anyway. Even if not, you can tolerate anything for two weeks (unless they chase you with chainsaws or something?) and it's a much more professional thing to do.

A lot of times it does hurt, most jobs now adays do a back ground check and ask for references. They may even contact this employer. So best bet is to give them your 2 weeks notice and let them know about your education. They should not hold you back on that.

Just quit this job is not the end of the world. If I were you I would of quitted the job long time ago if there not being understanding and make a big deal about everything. You don't have to write anything because when you quit mostly they all hate you

I suggest that you continue to be professional. Give them one week's notice and don't go into any details other than the time you need for school.
Should they beg you to stay and promise to be flexible with your classes again, simply and sweetly say that you're sorry, but no.
I ALWAYS check references and would really hestitate to hire someone who walked out on an employer.
Good luck!