This thesis develops a phenomenology of immersive cinematic spectatorship. During an immersive experience in the cinema, the images, sounds, events, emotions, and characters that form a fictional diegesis become so compelling that our conscious experience of the real world is displaced by a virtual world. Theorists and audiences have long recognized cinema’s ability to momentarily substitute for the lived experience of reality, but it remains an under-theorized aspect of cinematic spectatorship. The first aim of this thesis is therefore to examine these immersive responses to cinema from three perspectives – the formal, the technological, and the neuroscientific – to describe the exact mechanisms through which a spectator’s immersion in a cinematic world is achieved. A second aim is to examine the historical development of the technologies of visual simulation that are used to create these immersive diegetic worlds. My analysis shows a consistent increase in the vividness and transparency of simulative technologies, two factors that are crucial determinants in a spectator’s immersion. In contrast to the cultural anxiety that often surrounds immersive responses to simulative technologies, I examine immersive spectatorship as an aesthetic phenomenon that is central to our engagement with cinema. The ubiquity of narrative – written, verbal, cinematic – shows that the ability to achieve immersion is a fundamental property of the human mind found in cultures diverse in both time and place. This thesis is thus an attempt to illuminate this unique human ability and examine the technologies that allow it to flourish.