The acquisition and integration οf basic technical knowledge with knowledge gained through repeated experiences in a specific task domain are important to expertise development (e.g., Anderson, 1982. Boshuizen Schmidt, 1992. Riesbeck Schank, 1989. Schank Abelson, 1977. Tulving, 1985). Teaching writing skills should, therefore, include repeated practice in writing within a specific task domain.Educators have adopted writing programs such as Writing Across the Curriculum (WAC) and Writing in the Disciplines (WID), in part because they are consistent with this perspective. Instructors in these types οf programs emphasize the importance οf repeated, contextualized experiences for the development οf writing skills (e.g., Herrington, 1981. McLeod Maimon, 2000. Parks Goldblatt, 2000. Royster, 1992. Russell, 1992). Researchers have examined the effectiveness οf these programs at a general-program assessment level (see, e.g., White, Lutz, Kamusikiri, 1996. Witte Faigley, 1983). However, there is little research on the underlying cognitive theory for these programs (i.e., testing whether the repeated practice in writing within a specific task domain actually results in improved writing skills). The purpose of οf this study was to provide such evidence.Specifically, we investigated (a) whether repeated practice improves students’ writing skills and (b) after controlling for repeated practice, whether writing within a specific task domain improves students’ writing skills. From a curriculum-design perspective, it is important to distinguish these effects because WAC–WID programs have been implemented based on the belief that repeated, contextualized experiences are helpful in improving students’ writing skills. Our research design allowed us to separately test these effects, which contribute to our understanding οf the extent to whichcontextual-versus general-writing experiences lead to improved writing skills.