Description: Recent years have seen a series of policy initiatives in the UK that have variously enforced, incentivised or simply encouraged school-to-school collaboration. These initiatives have been targeted largely, though not exclusively, at schools in areas of relative social and economic deprivation. They have also been largely focused around two major strands of government education policy- raising standards and developing leadership capacity. This paper looks at the key findings emerging from such initiatives, and asks to what extent these constitute an emerging knowledge base about collaborative working between schools.The paper focuses on four major national initiatives: the Excellence in Cities (EiC) programme, launched in 2000, the Network Learning Communities (NLC) established by the National College for School Leadership in 2001, the Leadership Incentive Grant (LIG) programme from 2003-06, and the School Federations programme which has emerged since 2003. Methodology: The paper draws on published evaluations, both national and local, on interviews with key players- both within schools in the various initiatives and those who have contributed to evaluation activities, and on the author's own direct experience in supporting the development of EiC and LIG collaboratives. It analyses the available data in light of two questions: what are the conditions needed for school-to-school collaboration to be successful, and what implications do these conditions have for the attitudes and behaviours of school leaders? Conclusions: The paper identifies a number of barriers to effective collaboration, in a context where competition and choice continue to be driving forces within national policy, the government's interest in collaborative working notwithstanding. It also suggests that, to be successful, collaboration needs to be able to pull on powerful levers- here the development of common goals and the forms of evidence used to 'assess' school performance are critical. Nevertheless, conditions that are necessary if school-to-school collaboration is to be effective emerge from the analysis, including; · The presence of incentives that encourage key stakeholders to explore the possibility that collaboration may be in their own interests; · The development of collective responsibility for bringing about improvements in all the partner organisations; · Headteachers and other senior staff in schools who are willing and able to drive collaboration forward; · The creation of common improvement agendas that are seen to be relevant to a wide range of stakeholders; · External help from credible consultants/advisers (from LEA or elsewhere) who have the confidence to learn alongside their school-based partners; and · A willingness and desire amongst LEA staff to support and engage with the collaborative process, exploring and developing new roles and relationships.The paper also sets out a number of propositions about school leadership practices that foster effective collaborative effort, including; · The need for school leaders to accept joint responsibility for the performance of all students in all of the partner schools · A focus on teaching and learning with deliberate and systematic strategies for school improvement · A willingness to acknowledge and draw on strengths in partner schools· The commitment to develop new management roles and systems needed to support the development of the collaborative · Distributed leadership- both horizontally and vertically- with direct contact between schools and the capacity to take decisions spread down through the schools' structures.