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While « classical » pseudoclefts have been widely studied (Bolinger 1972 ; Delahunty 1984 ; Collins 1991 ; Fichtner 1993 ; Kim 2007 ; Traugott 2008 ; Patten 2010), all-clefts appear to have been comparatively neglected, given the inordinate frequency of this variant in online corpora. This article aims to show that three types of pseudoclefts, namely what-pseudoclefts, all-clefts with relative pronoun that and all-clefts with zero relative pronoun, whose initial nominal relative clause regularly share the same set of lexical verbs (namely, know, need, take, want and do), make up a micro-system in which the three variants represent three successive steps of meaning construction. Second, the derivation of all-clefts reveals that the universal proform all does not belong in the original clause from which the surface pseudocleft construction originates but only in the last step of the derivation process. Finally, this article explains why all is used in the all-cleft pattern whilst everything is excluded because of all’s syntactic properties, i.e. its compatibility with uncountable nouns.