We prove that hyperbolic 3-manifolds are geometrically inflexible: a unit quasiconformal deformation of a Kleinian group extends to an equivariant bi-Lipschitz diffeomorphism between quotients whose pointwise bi-Lipschitz constant decays exponentially in the distance from the boundary of the convex core for points in the thick part. Estimates at points in the thin part are controlled by similar estimates on the complex lengths of short curves. We use this inflexibility to give a new proof of the convergence of pseudo-Anosov double iteration on the quasi-Fuchsian space of a closed surface, and the resulting hyperbolization theorem for closed 3-manifolds that fiber over the circle with pseudo-Anosov monodromy.Theorem 1.1 (Geometric Inflexibility). Given a hyperbolic 3-manifold M, a K-bi-Lipschitz diffeomorphic hyperbolic 3-manifold M and an > 0, there is a diffeomorphism Φ: M → M whose bi-Lipschitz distortion in the -thick part of the convex core C(M ) decays exponentially with the distance from ∂C(M ) with the rate of decay depending only on , K and the topology of ∂M . See Theorem 5.6 for a more precise version.Proposition 3.1 (Hodgson-Kerkchoff). Let M be a compact manifold with piecewise smooth boundary and η be a harmonic strain field. ThenThe following inequality will allow us to control the boundary term in terms of pointwise bounds on the norms of η and Dη.Lemma 3.2. We have η 2 + Dη 2 2 * Dη ∧ η .Proof. The inequality follows from the fact that η − * Dη 2 0.The following lemma is the first step in showing that the formula from Proposition 3.1 holds on some noncompact manifolds if the strain field is bounded.Lemma 3.3. Let M be a complete hyperbolic 3-manifold that is exhausted by compact submanifolds M n with the area of ∂M n bounded above. If η is a harmonic strain field with the pointwise norms η and Dη bounded above, then the L 2 -norm of η and Dη is finite.Proof. By Proposition 3.1,Since both the area of ∂M n and the pointwise norms of η and Dη are bounded, Lemma 3.2 implies that the right-hand side is bounded. This implies that the L 2 -norm on M is finite.Let P n be a finite (1/n)-net on ∂M . DefineLemma 3.4. For all but an isolated set of t > 1/n, M n (t) is a manifold with piecewise smooth boundary.Proof. If the boundary of M n (t) is not a manifold with piecewise smooth boundary, then there is a geodesic of length 2t in M with endpoints in P n . The set of lengths of geodesics in M with endpoints in P n is a discrete subset of R, so M n (t) must be a manifold with piecewise smooth boundary for all but an isolated set of values for t.