This is Volume 9, Number 3 (2000) special issue of the Journal of Learning Sciences and focuses on Design Education. Design as a vehicle for applying and extending content knowledge is central to engineering education. In this issue the reader is offered three articles on middle- school-age children learning in the context of design. Two articles report on research projects in in formal educational settings with large numbers of students; the other chronicles one girl's learning over a weekend in an informal online setting.