For W_N minimal model CFT's at Large N, we formulate a nonlinear field theory of primary operators. A classification of single-trace operators is given first based on which an interacting field theory operating in Fock space is built. A hamiltonian is constructed with the property that it reproduces exactly the spectrum of conformal dimensions of all the primaries. This field theory is characterized by cubic (and quartic) interactions with G=1/N as an interaction parameter. It is seen that the 1/N nonlinear representation contains the interactions and structure known from Matrix-vector models.

44 pages. v4: misprints corrected, minor improvement