Light-colored phenolic-modified rosin esters, suitable for use as, for example, tackifiers in adhesive compositions, are provided. The resins may be prepared by reacting together rosin, a phenolic compound, formaldehyde or a reactive equivalent thereof, and a non-phenolic hydroxyl-containing organic compound in the presence of at least one lightening agent selected from phenol sulfide compounds, phosphorous acid, esters of phosphorous acid, and hypophosphite salts. The formaldehyde or reactive equivalent is present in an amount ranging from about 1.1 to about 3.5 equivalents of -CHO moieties per 1 equivalent of Ar-OH moiety of the phenolic compound, in order to obtain rosin esters having desirably low color, and adequately low molecular weight to effectively function as tackifiers.