This book represents a selected group of manuscripts from lecturers participating in the NATO/Gulbenkian Foundation sponsored course on Somatic Cell Genetics held May 31 to June 12, 1981 in the Hotel Montechoro in the Algarve of Portugal. The text will provide those students who could not attend the meeting with a current survey of important advances in the field of Somatic Cell Genet­ ics. It is not possible to recapture here all the lectures, semi­ nar discussions, student and faculty interactions, the ambience of the Algarve and the time devoted exclusively to scientific discus­ sion. In summary, I feel that this book is good, but the scien­ tists, the students, and the entire course were better. Somatic Cell Genetics is a broad subject area and one which has contributed significantly to Our understanding of the mammalian cell. Drs. Caskey, Buttin, Siminovitch, and Lechner elected in designing the course to focus on the results obtained with cultured animal cells.