Title: The dualizing spectrum of a topological group Author: John R. Klein AMS subjclass: Primary: 55P91, 55N91, 55P42, 57P10. Secondary: 55P25, 20J05,18G15. Address: Dept. Of Mathematics, Wayne State University, Detroit, MI 48202 e-mail: klein@math.wayne.edu Abstract: To a topological group G, we assign a naive G-spectrum D_G, called the "dualizing spectrum" of G. When the classifying space BG is finitely dominated, we show that D_G detects Poincare duality in the sense that BG is a Poincare duality space if and only if D_G is a homotopy finite spectrum. Secondly, we show that the dualizing spectrum behaves multiplicatively on certain topological group extensions. In proving these results we introduce a new tool: a "norm map" which is defined for any G and for any naive G-spectrum E. Applications include: (1) a homotopy theoretic solution to a problem posed by Wall which says that in a fibration sequence of finitely dominated spaces, the total space satisfies Poincare duality if and only if the base and fiber do. (2) An entirely homotopy theoretic construction of the Spivak fibration of a finitely dominated Poincare duality space. (3) A new proof of Browder's theorem that every finite H-space satisfies Poincare duality. (4) We show how to define a variant of Farrell-Tate cohomology for any topological or discrete group G, with coefficients in any naive equivariant cohomology theory E. We prove a vanishing result for this theory. In an appendix, we identify the homotopy type of D_G for certain kinds of groups. The class includes all compact Lie groups, torsion free arithmetic groups and Bieri-Eckmann duality groups. (This paper has already been accepted for publication in Math. Annalen.)