Spectral enrichments of model categories Daniel Dugger ddugger@math.uoregon.edu Abstract: We prove that every stable, combinatorial model category has a natural enrichment by symmetric spectra (really a natural equivalence class of enrichments). This in some sense generalizes the simplicial enrichment of model categories provided by the Dwyer-Kan hammock localization. As a particular application, we associate to every object in a stable, combinatorial model category a certain "homotopy endomorphism ring spectrum". The homotopy type of this ring spectrum is preserved by Quillen equivalences, and so serves as an invariant of model categories.