<p>You can only apply to one university as early decision because it is binding.
You can apply to more than one university as early action but only if it isn't SCEA. If it is SCEA then you can only apply early action to that school.</p>
<p>Most schools offer ED or EA and some offer both, it would be better to come up with a list of schools that appeal to you and then research what policy they have.</p>
<p>Man, I just posted on another thread that I agree with Pyar, and I have to say I do once again, though this time primarily with the second paragraph.</p>
<p>With regard to application restrictions, I will be a bit more specific, though the previous info is certainly correct.
You can only apply ED to one university. If admitted ED, you must attend this school. If rejected or deferred, you are free to apply elsewhere.
The only situation in which two EDs could possibly be done, is that some schools have a second ED round, generally with a similar deadline as RD. Thus, if you were rejected from your ED school, but had a definite second choice, you could apply there ED2 if they had it.
Some ED schools allow you to also apply EA to other schools, but if admitted to the ED school you are still bound to go there, and your EA result does not matter. Some ED school do not allow this.
Most EA schools allow you to apply to multiple places, though a few, the SCEA schools, do not.
ANY school, whether ED or EA (at least, as far as I'm aware of, I'm sure people can drudge up <em>some</em> school that disagrees), will allow you to apply to RD or Rolling schools prior to discovering your acceptance (some schools' RD deadlines fall prior to finding out ED results, so clearly it would be unethical to forbid these applications), but if the school was ED, and you are accepted, you must then withdraw your app to the other schools.</p>