ASE's Continuing Professional Development (CPD) programme is designed and run by people--teachers--who understand the pressures. They realise that the solution to good professional development is not to give the teacher extra work to do, but to draw added value from the tasks which the teacher is engaged in already or soon will be--and, importantly, which will further the aims of the school. Many CPD participants work in secondary science departments, usually mentored by their own heads of department. In this article, the author describes this flexible programme based firmly on the needs of individual teachers and their schools.