◎ Contents Part Ⅰ The problem of school mix Part Ⅱ The Wellington schools Part Ⅲ Theory, practice, policy and research ◎ Abstract Does an effective school really come about through the actions of teachers and s chools leaders, or does it also require an advantaged school intake? This quesion reflects a longstanding research debate about whether or not the social class mix of a school's student intake has much effect on individual ahievement.; This text presents evidence suggesting that school mix is likely to be important because of the way many school processes are deeply influenced by student intake har acteristics. Low socioeconomic schools face numerous intake-related constraints which make them highly resistant to improvement efforts. By suggesting that "fai ling" schools are often overwhelmed rather than inefftive, this text provides a sympathetic reappraisal of the performance of teachers and school leaders in s uch schools. It also offers a critical response to the often unrealistic claims of the school effectiveness and school improvement movement and a fresh critique of market reforms in education.