We will examine two dimensional conformal field theories with W_N symmetry in the "irrational" regime. For N <= 6 explicit use of the algebra allows for the computation of the Kac matrix and requiring positivity yields non-trivial constraints on the dimension of non-vacuum primary states. For general N we will examine the structure of null states and make a conjecture for the corresponding constraints. Comments will also be made about the effect of these constraints on the dual holographic theories in AdS_3.