TITLE: Prerequisites for P-adic Representations
QUESTION [6 upvotes]: I wonder what the prerequisites for learning the representation theory of reductive groups over a p-adic field are? Can someone recommend me any book or article for learning this theory if I wanna clearly know what this theory is about and what kind of applications this theory has? 
I just know some fundamental concepts, like Part 1 of Serre's "Linear rep'ns of finite groups", of the rep'ns of finite groups and the structure of p-adic fields. Thanks!

REPLY [6 votes]: When I learned this material, 10 or so years ago, I read Cartier's article in Corvalis (linked to by Thomas in the comments above),
and then Casselman's notes (mentioned by Ramin).  My experience has been that all of this material is a little dry and difficult to learn (due to lack of apparent motivation) if it is not coupled with an understanding of its relationship to the global theory of automorphic forms.  In turn, I find automorphic forms difficult to think about without having the link to the classical case of modular forms.    
Unfortunately, while there is a lot of literature available which explains the relations between the classical theory of modular forms and the more representation-theoretic and more general theory of automorphic forms, I found a lot of it unsatisfying when I was learning this material for the first time.  One article that I like is Deligne's expository article in LNM 349, in which he concretely passes from the theory of modular forms on the upper half-plane to the representation-theoretic view-point of functions on $GL_2$ of the adeles.  It might at least serve as a helpful supplement to more comprehensive treatises such as those of Gelbart or Bump.