An efficient method for the preparation of 1,3-dithiolanes from aldehydes and ketones with 1,2-ethanedithiol in the presence of a catalytic amount of anhydrous indium(III) chloride is reported. A mild and highly chemoselective thioacetalization of carbonyl compounds using indium(III) chloride as the catalyst is also described. The desired products were obtained in 71–95% yield.