Quote Originally Posted by TheOOB View Post
They have not yet released any sort of multi classing rules, but I can pretty much guarantee it won't work like it does in 3e. My guess, It'll either be something like 4e where you can kinda sort get other class features, or like 2e where you can have a sort of dual advancement type deal.
Quote Originally Posted by enworld

Multiclassing: "...here's what we have in mind. When you gain a level, you can choose any class and gain a level in that class, much in the same way that it functioned in 3rd Edition. Of course, those of you who play or played 3E know that there can sometimes be issues with this, and if you aren't careful you can build a character that struggles with effectiveness at higher levels. However, there's a lot of good that comes out of this system, including organic character growth, expansive character building options without the need for large swathes of material, and the ability to express your character's specialties through a unique mix of classes." - Rodney Thompson.
Admittedly not neccessarily up-to-date.