Given the participatory, immersive Web 2.0 culture that characterizes digital experiences today, what is traditionally understood as \u27usability\u27 is insufficient to drive the engagement Web 2.0 audiences both crave and have come to expect from best-in-class interfaces. Thus, this dissertation presents a \u27constructivist\u27 vision of usability that helps designers \u27speak\u27 to audiences who demand excellence, and who will leave when confronted with mediocrity. The constructivist practice of usability occurs through what I call \u27interpellative design.\u27 Interpellative design is both a complement to, and a critique of, \u27accommodationist\u27 approaches to usability (Howard, 2010a) which tend to be associated with technical problem solving (Jordan, 2001), ease of use (Shedroff, 2001), and \u27expedient\u27 solutions (Katz, 1992) to mechanistic problems. As part of the under-theorized \u27constructivist\u27 approach to usability (Howard, 2010a), interpellative design allows usability to remain a \u27problem-solving discipline\u27 (Jordan, 2001); however, its focus on beauty, argument, and the figural dialogue between designers and users extends the purview of usability into non-algorithmic pursuits. To describe a constructivist approach to usability, I outline a theoretical taxonomy which identifies factors at play in interpellative user interfaces. An \u27interpellative interface\u27 is one which calls out or \u27hails\u27 (Althusser, 1971a) users and indicates that a given interface is a viable \u27place\u27 in which they can exert influence, accomplish tasks, or solve problems. The hail is facilitated through the construction of a habitus and use of social capital (Bourdieu, 1984). Briefly, a habitus is the space into which users are interpellated, and acts and artifacts of social capital are expressions of how they belong in that space. In examining how these factors manifest in digital interfaces, I argue that the constructivist approach to usability enacted through interpellative design enables usability engineers to identify flaws in interfaces that were not apparent before the mechanisms of habitus and social capital were explicated. The lens of interpellative design allows usability engineers to address the constructivist concerns pertaining to emotion, visual communication, and other types of \u27distinctions\u27 (Bourdieu, 1984) that could not be \u27seen\u27 before
