Abstract: In order to locally control a space-time which satisfies the Einstein equations, what are the minimal assumptions one should make on its curvature tensor? The bounded L2 curvature conjecture roughly asserts that one should only need L2 bounds on the curvature tensor on a given space-like hypersuface. I will present the proof of this conjecture, which sheds light on the specific nonlinear structure of the Einstein equations. This is joint work with S. Klainerman and I. Rodnianski.