  This paper is a contribution to "neo-stability" type of result for abstract
elementary classes. Under certain set theoretic assumptions, we propose a
definition and a characterization of NIP in AECs. The class of AECs with NIP
properly contains the class of stable AECs. We show that for an AEC $K$ and
$\lambda\geq LS(K)$, $K_\lambda$ is NIP if and only if there is a notion of
nonforking on it which we call a w*-good frame. On the other hand, the negation
of NIP leads to being able to encode subsets.
