This volume contains the proceedings of the Regulators III Conference, held from July 12 to July 22, 2010, in Barcelona, Spain. Regulators can be thought of as realizations from motivic cohomology, which is very difficult to compute, to more computable theories such as Hodge, Betti, l-adic, and Deligne cohomology. It is a very intricate subject that thrives on its interaction with algebraic K-theory, arithmetic geometry, number theory, motivic cohomology, Hodge theory and mathematical physics. The articles in this volume are a reflection of the various approaches to this subject, such as results on motivic cohomology, descriptions of regulators, a revisiting of a number of fundamental conjectures (such as new results pertaining to the Hodge and standard conjectures), and more.