This study investigated the effects of different types of elaboration on second ranguage (L2) reading comprehension and incidentar vocabulary learning. Five hundred and seven 9th grade students in Korea were randomly assigned to one of six condition groups: Control, Unmodified, Simplified, Lexically Elaborated, Structuralry Elaborated, or Lexically & Structuraly Elaborated. Both simplification and elaboration increased L2 comprehension, assessed by 20 multiple-choice test items. Although students reading the simplified versions scored highest, no statisticalry significant differerce was found between the effects of simplification and elaboration. Among the different types of elaboration, structural elaboration appeared to be more effective than lexical elaboration, but not significantly so. The results of three vocabulary test–form, meaning, and delayed meaning recognition–showed no significant efferts of text modificatiotr on incidental vocabulary learning
