'Cameron's masterly style allows him to cover an enormous amount of ground ... it is a delightful book, which every group-theorist should have, either to read systematically or to dip into in odd moments: a randomly-chosen page almost certainly contains something new and instructive.' Gareth A. Jones, Bulletin of the London Mathematical Society ' ... an excellent concise account of the modern theory of permutation groups ...' W. Knapp, Zentralblatt MATH