On the basis of 572 examples taken from seven million-word corpora of written English the present study--which complements the spoken data-based studies of Oberlander & Delin (1996) and Weinert & Miller (1996)--explores the relationship between information structure and discourse role with reversed what-clefts. The study confirms the typically summative, internal-referencing, and stage-ending-roles of the informational type upon which previous studies have concentrated (the statistically dominant type, with minimally informative highlighted element and relative clause). A second type observed by Oberlander & Delin (1996), with an "informative presupposition" or "comment clause", is found to occur stage-medially rather than as an ending, and furthermore to have a "pivotal" (both backward- and forward-looking) discourse role. Two further types of reversed what-cleft with an informationally new highlighted element are identified. Both can occur stage-initially, and share some similarities with basic what-clefts and it-clefts in their discourse behaviour. (Contains 4 tables.)