Abstract: Microcapsules containing a solution or dispersion of a colorant, especially a solution of an oil-solubilized sulfur dye, in an organic liquid having a vapor pressure below 20 mm Hg at 25.degree. C. can be coated on a side of a sheet of paper for use in pressure-sensitive carbonless copy systems. The solutions of the oil-solubilized sulfur dyes, i.e. 1) colored products of the oxidation of a leuco sulfur dye, leuco sulfurized vat dye or reaction product of a leuco dye or sulfurized vat dye with a cationic compound and 2) colored reaction products of a solubilized sulfur dye with a cationic compound also constitute an aspect of the invention, as do microcapsules whose walls contain an opacifying agent incorporated therein.