Title: Subalgebras of group cohomology defined by infinite loop spaces Authors: John R. Hunton Bj"orn Schuster MSC: 20J06 55N20 55P47 (primary), 55R40 19A22 55P60 (secondary) arXiv: math.AT/0112169 Addresses: The Department of Mathematics and Computer Science, University of Leicester, University Road, Leicester, LE1 7RH, England Department of Mathematics, University of Wuppertal, Gaussstr.~20, D-42097 Wuppertal, Germany. Status: Submitted. Abstract: We study natural subalgebras Ch_E(G) of group cohomology defined in terms of infinite loop spaces E and give representation theoretic descriptions of those based on QS^0 and the Johnson-Wilson theories E(n). We describe the subalgebras arising from the Brown-Peterson spectra BP and as a result give a simple reproof of Yagita's theorem that the image of BP^*(BG) in H^*(BG;F_p) is F-isomorphic to the whole cohomology ring; the same result is shown to hold with BP replaced by any complex oriented theory E with a map of ring spectra from E to HF_p which is non-trivial in homotopy. We also extend the constructions to define subalgebras of H^*(X;F_p) for any space X; when X is finite we show that the subalgebras Ch_{E(n)}(X) give a natural unstable chromatic filtration of H^*(X;F_p).