The Institute of Group Analysis (IGA) celebrates forty years from its foundation with the publication of two new volumes tracing the foundations and applications of Group Analysis. The first volume ('Foundations') aims to publicise the foundations of group analysis (with the earliest papers of Foulkes) as well as the most influential theoretical contributions by pillars of modern group analysis, such as Pines, Brown, and Hopper. The reader will be able to see the development of Group Analysis, form an opinion about the trajectory that it follows, and judge which way the tradition of openness and creative integration of diverse theoretical contributions will lead in the twenty-first century.The second volume ('Applications') focuses on the numerous fields of work that use group analytic principles. Workers in the field of forensic psychotherapy would now consider it a great omission if they did not use some form of group analytic intervention, as would professionals dealing with those who manifest personality disorders, or those who work with different age groups, such as adolescents. Group analysis has made significant contribution to organisational work, to feminism and anti-discrimination (including anti-racism) as well as in education. The separate school of family therapy was based on group analysis, and in fact the first course of family therapy was based on group analysis and the Institute of Family Therapy was founded by (among others) the founders of IGA. This work is meant to give easy access to the first expressions of cardinal concepts, such as the matrix, the laws of group analysis, and the notion of pseudo-problems and false dichotomies. It is hoped that it will form not only an essential source book but also will indicate the way contemporary practitioners can integrate the new developments - not included in these volumes - from spectrums as diverse as mentalisation and epigenetics.