Molecular glass based planarizing compositions for lithographic processing are disclosed. The processes generally include casting the planarizing composition onto a surface comprised of lithographic features, the planarizing composition comprising at least one molecular glass and at least one solvent; and heating the planarizing composition to a temperature greater than a glass transition temperature of the at least one molecular glass. Exemplary molecular glasses include polyhedral oligomeric silsesquioxane derivatives, calixarenes, cyclodextrin derivatives, and other non-polymeric large molecules.