This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License Newcastle University ePrints - eprint.ncl.ac.uk Pickles A, Harris V, Green J, Aldred C, McConachie A, Slonims V, Le Couteur A, Hudry K, Charman T, Pact Consortium. Treatment Mechanism in the MRC Pre-school Autism Communication Trial: Implications for study design and parent-focussed therapy for children. Journal of Child Psychology and Psychiatry 2015, 56(2), 162-170. Copyright: This is the peer reviewed version of the above article, which has been published in final form at: http://dx.doi.org/10.1111/jcpp.12291 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Date deposited: 15/12/2015