This volume includes the proceedings of a workshop on Invariant Theory held at Queen's University (Ontario). The workshop was part of the theme year held under the auspices of the Centre de recherches mathématiques (CRM) in Montreal. The gathering brought together two communities of researchers: those working in characteristic 0 and those working in positive characteristic. The book contains three types of papers: survey articles providing introductions to computational invariant theory, modular invariant theory of finite groups, and the invariant theory of Lie groups; expository works recounting recent research in these three areas and beyond; and open problems of current interest. The book is suitable for graduate students and researchers working in invariant theory. Titles in this series are copublished with the Centre de Recherches Mathématiques. Readership Graduate students and research mathematicians interested in invariant theory. Table of Contents  G. Bousquet and L. MoserJauslin  A local study of embeddings of complexity one
 H. Derksen  Constructive invariant theory
 H. Derksen and G. Kemper  On global degree bounds for invariants
 P. Fleischmann  On invariant theory of finite groups
 A. G. Helminck  Combinatorics related to orbit closures of symmetric subgroups in flag varieties
 F. Hivert and N. M. Thiéry  Deformation of symmetric functions and the rational Steenrod algebra
 W. van der Kallen  Cohomology with Grosshans graded coefficients
 D. B. Karagueuzian and P. Symonds  The module structure of a group action on a polynomial ring: examples, generalizations, and applications
 N. E. Kechagias  An invariant theoretic description of the primitive elements of the mod\(p\) cohomology of a finite loop space which are annihilated by Steenrod operations
 F. Knop  On Noether's and Weyl's bound in positive characteristic
 M. D. Neusel  Comparing the depths of rings of invariants
 V. L. Popov  Moment polytopes of nilpotent orbit closures; dimension and isomorphism of simple modules; and variations on the theme of J. Chipalkatti
 Z. Reichstein  Compressions of group actions
 L. G. Rybnikov  Commutativity of weakly commutative Riemannian homogeneous spaces
 G. W. Schwarz  Group actions and quotients for compact Lie groups and algebraic groups
 J. Segal  Notes on invariant rings of divided powers
 R. J. Shank  Classical covariants and modular invariants
 A. V. Smirnov  Classification of nearly closed orbits for the action of semisimple complex linear groups on the projective spaces
 N. M. Thiéry and S. Thomassé  Convex cones and SAGBI bases of permutation invariants
 D. L. Wehlau  Some problems in invariant theory
 R. M. W. Wood  The Peterson conjecture for algebras of invariants
 O. Yakimova  Weakly symmetric and weakly commutative spaces
