ABSTRACT The two oldest forms of psychohistory, as generically defined, are psychobiography (Idiographic, qualitative, and single-case) and historiometry (nomothetic, quantitative, and multiple-case) In practice this distinction gets blurred, both because psychobiography is often nomothetic (e g, psychoanalytic) and because historiometry may work with N= 1 After outlining the assets of single-case historiometry, a specific case is given in an analysis of the 154 sonnets of William Shakespeare These sonnets were first reliably differentiated on aesthetic success according to an archival popularity measure, and then this relative ment was predicted using content analytical measures suggested by research on artistic creativity The superior sonnets (a) treat specific themes, (b) display considerable thematic richness in the number of issues discussed, (c) exhibit greater linguistic complexity as gauged by such objective measures as the type-token ratio and adjective-verb quotient, and (d) feature more primary process imagery (using Martindale's Regressive Imagery Dictionary) After discussing how these results can enlarge our general understanding of artistic creativity as well as our specific appreciation of Shakespeare's creativity, the potential application of single-case historiometry to intrinsically psychobiographical problems is examined