Link to this article: http://journals.cambridge.org/abstract_S014338570900039XHow to cite this article: RAFAEL DE LA LLAVE and ALISTAIR WINDSOR (2010). Livšic theorems for non-commutative groups including diffeomorphism groups and results on the existence of conformal structures for Anosov systems.Abstract. The celebrated Livšic theorem [A. N. Livšic, Certain properties of the homology of Y -systems, Mat. Zametki 10 (1971), 555-564; A. N. Livšic, Cohomology of dynamical systems, Izv. Akad. Nauk SSSR Ser. Mat. 36 (1972), 1296-1320] states that given a manifold M, a Lie group G, a transitive Anosov diffeomorphism f on M and a Hölder function η : M → G whose range is sufficiently close to the identity, it is sufficient for the existence of φ : M → G satisfying η(x) = φ( f (x))φ(x) −1 that a condition-obviously necessary-on the cocycle generated by η restricted to periodic orbits is satisfied. In this paper we present a new proof of the main result. These methods allow us to treat cocycles taking values in the group of diffeomorphisms of a compact manifold. This has applications to rigidity theory. The localization procedure we develop can be applied to obtain some new results on the existence of conformal structures for Anosov systems.