The Wiley Handbook of What Works in Child Maltreatment: An Evidence-Based Approach to Assessment and Intervention in Child Protection, First Edition. Edited by Louise Dixon, Daniel F. Perkins, Catherine Hamilton-Giachritsis, and Leam A. Craig. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd. Overview and Structure of the Book Louise Dixon 1 , Daniel F. Perkins 2 , Catherine Hamilton‐Giachritsis 3 and Leam A. Craig 4 1 Victoria University of Wellington, New Zealand 2 The Pennsylvania State University, USA 3 University of Bath, UK 4 Forensic Psychology Practice Ltd, UK 4 University of Birmingham, UK 4 Birmingham City University, UK Introduction The idea that ‘something’ works in offender rehabilitation suffered a devastating blow in the 1970s following reviews that ‘nothing worked’ (Martinson, 1974). This conclusion was later attributed to the poor methodology and research designs of studies investigating this issue (Lipton, Martinson & Wilks, 1975), rather than an inability to rehabilitate behaviour. However, the concept of ‘nothing works’ led to a body of research that investigated which practices are effective in the rehabilitation of people who offend, often referred to as the What Works litera- ture (Craig, Dixon & Gannon, 2013). The What Works literature is based on an overarching principle that highlights the need for empirically rigorous evidence‐based practice. Several systems have been developed to aid the evaluation of the quality of evidence on the efficacy of particular therapeutic techniques and their use with particular groups of people. The work has been subsumed under the category ‘What Works in the treatment and management of offend- ers to reduce crime’. The three main systems of empirical evaluation used to examine the quality of outcome studies that are most often referred to in the literature are: (i) the American Psychological Association (APA) Chambless and colleagues’ system (Chambless & Hollon, 1998; Chambless, Baker, Baucom et al., 1998; Chambless & Ollendick, 2001); (ii) Sherman, Gottfredson, MacKenzie et al.’s (1997) ‘levels’ system for reviewing the quality of evidence and intervention; and (iii) the Cochrane System (Higgins & Green, 2006/2008/2011). In brief, the APA system examines the quality of evidence from outcome studies on the effectiveness of psychological therapy. Sherman, Gottfredson, MacKenzie et al.’s (1997) report to the US Congress described a ‘levels’ system for reviewing the quality of evidence supporting any given intervention in the field of criminal behaviour. 1 COPYRIGHTED MATERIAL