This dissertation is a study of the early career of the American artist Joan Jonas that spans the years 1970-1984. At the turn of the 1970s, Jonas was one of the first artists to pick up a video camera. Exploring "live" video's unique capacity to mediate the present moment, Jonas actively integrated the technology into her live pieces, which are some of the earliest examples of what was then first called "performance art." Performance art has often been aligned with presence. In contrast, I argue that what at stake in the proliferation of live artworks by Jonas and others that merged performance and video was not a reserve of unmediated experience, but a presence that was newly technologized: telepresence. As Jonas investigated the novel ability to perform at a distance enabled by electronic media, her work led somewhere surprising: to telegraphy, telepathy, and the earliest telephones---"tele"-technologies that appear long obsolete (or completely fantastical). Evoking optical telegraphs, spirit mediums, speaking trumpets, and science fictional prostheses, Jonas's early oeuvre reactivates the historical contexts and unrealized potentials surrounding these dead media. In so doing, she illuminates enduring formations of the body, subjectivity, and teletechnology underlying not only the twinned emergence of performance and video art in the 1970s, but also telepresence as a seemingly very contemporary (and increasingly pervasive) category of experience.