This advanced EURACHEM textbook is designed for training, teaching and continuing studies providing an in-depth coverage of current teaching and training issues in the field of Quality Assurance in Chemical Measurement. The CD-ROM accompanying the book contains course materials of 15 experienced lecturers on more than 300 overheads (graphics and text) as ready-to-use Powerpoint R documents. The book will serve as a reference text and source of course materials for lecturers and as an advanced textbook for analytical chemistry students and professionals in industry and service labs.