We investigate a new hybrid-model universe containing two types of dark matter, one ``warm'' and the other ``hot.'' The hot component is an ordinary light neutrino with mass \ensuremath{\sim}25${\mathit{h}}^{2}$ eV while the warm component is a sterile neutrino with mass \ensuremath{\sim}700${\mathit{h}}^{2}$ eV. The two types of dark matter arise entirely within the neutrino sector and do not require separate physical origins. We calculate the linear transfer functions for a representtaive sample of warm-plus-hot models. The transfer functions and results from several observational tests of structure formation are compared with those for the cold-plus-hot models that have been studied extensively in the literature. On the basis of these tests we conclude that warm-plus-hot dark matter is essentially indistinguishable from cold-plus-hot dark matter, and therefore provides a viable scenario for large scale structure. We demonstrate that a neutrino mass matrix can be constructed which provides the requisite dark matter constituents, while remaining consistent with all cosmological bounds.