The aim of this book is to provide just such a series of protocols for the teaching of practical molecular biology. The idea arose following the success of several Workshops in Molecular Biology, organized and taught by staff in the Biology Department of the Hatfield Polytechnic. Gradually, the protocols used in the workshops have been incorporated into the Hatfield undergraduate and postgraduate teaching programs and have now been collected together to form a book. The lecturers and demonstrators in these workshops and courses, together with respected authorities from other institutions, have contributed their tried and tested protocols to this book so that others may more readily incorporate material central to modem molecular biology into their own undergraduate and beginning graduate-level courses, or indeed even develop similar laboratory workshops in their own institutions.