Description: During the last few years the English Government's strategies for improving education have placed increased emphasis on the need for schools to work together. This may, in part, be a recognition of some of the consequences of promoting competition between schools as a means of motivating their improvement efforts over the previous decade. Certainly there is evidence that, within urban contexts, an over-emphasis on competition can lead to certain schools and, indeed, certain groups of learners, being disadvantaged as they get left behind in the race to 'improve standards' (Thrupp, 2001).Working with colleagues, our own work has focused on school-to-school cooperation as a strategy for school improvement in such challenging contexts. These experiences lead us to see the potential of such forms of cooperation. They have also made us aware of the widespread and serious efforts that are being made to explore what this might mean in practice. However, most of these efforts must be seen as acts of faith, since there is very little research that demonstrates how and when such approaches do lead to positive outcomes, nor, indeed, evidence that can be used to guide action in the field. This paper will present evidence about the processes and outcomes involved in order to throw light on the most effective means of achieving positive outcomes. It will be based on case study accounts of six groups of schools. These examples will vary from groups that have volunteered to work together, through to groups that have done so in the context of incentives and others that have been subject to external pressure to collaborate. The groups were chosen because they were well established and there was some evidence that they are having an impact on practice in the member schools, particularly those facing challenging circumstances. A theoretical basis for the study was provided by our earlier work in this area (see Ainscow & West, 2006). Further leads arose from an analysis of lessons that have emerged from four major national initiatives that have encouraged schools to work together. These initiatives were: Excellence in Cities, the Leadership Incentive Grant, Networked Learning Communities and Federations.Data were collected through observation and interview to analyse the impact of the cooperative efforts that had taken place. These outcome data were then be analysed in relation to evidence about process, using a coding system corresponding to emerging themes. An audit trail was also created in order that claims about the relationship between process and outcomes could be subjected to scrutiny (Schwandt & Halpern, 1988). This led to an evaluative case report for each group of schools. Methodology: Data were collected through observation and interview to analyse the impact of the cooperative efforts that had taken place. These outcome data were then be analysed in relation to evidence about process, using a coding system corresponding to emerging themes. An audit trail was also created in order that claims about the relationship between process and outcomes could be subjected to scrutiny (Schwandt & Halpern, 1988). This led to an evaluative case report for each group of schools. Conclusions: Through a close scrutiny of the work of the six groups of schools, the paper will:· Analyse the development of school-to-school cooperation that is intended to help increase the participation and improve the learning of students in challenging contexts;· Evaluate the contribution of these activities to student achievement and progress; and· Develop greater theoretical understandings of collaborative practices and how they can be encouraged and sustained.