Fleshing out the definition of comprehensive education to include vital issues related to the act of teaching, this article considers reforms to be undertaken by practitioners alongside the political legislation required to achieve a fully comprehensive system of secondary schools. The effects of selection, such as the widening attainment gap, the impact of external testing and the culture of testing, together with the growth of setting and streaming are considered. There is a further examination of the relationship between the learner and the teacher, and the deeply influential results of segregation on children's self-image and readiness to learn. Finland is offered as a model of freedom from testing and successful, wholly non-competitive, mixed-ability teaching.