In this thesis, I seek to understand what shaped the development of television, tracing the technology back to its earliest roots. In existing literature, the history of television in its formative years (before World War II), has largely been presented in technologically deterministic terms, culminating in the ‘goal’ of adding ‘sight to sound’ – producing a wireless set with pictures. Most of the existing literature focuses on ‘hero’ figures such as British inventor John Logie Baird and his electro-mechanical television systems, or on corporate narratives such as that of RCA in the United States in developing all-electronic television. In contrast to such an approach, I will concentrate on the transnational networks linking individuals and companies, and on the common external factors affecting all of them. Some networks could operate simultaneously as rivals and collaborators, as was the case with companies such as Marconi-EMI in Britain and RCA in the United States. Senior managers and researchers such as Isaac Shoenberg at Marconi-EMI and Vladimir Zworykin at RCA played significant roles, but so too did relatively obscure figures such as Russian scientist Boris Rosing and British engineer Alan A Campbell Swinton. I will draw on newly available sources from Russia and the USSR, on over-looked sources in Britain and the United States, and on replicative technology to re-examine the story. The new material, coupled with the transnational networks approach, enables fresh insights to be gained on issues of simultaneity of invention and on contingency in the development and initial deployments of the technology. By using these fresh primary sources, and by re-interpreting some aspects of the numerous existing secondary sources, I will show that the ‘wireless with pictures’ model was not inevitable, that electro-mechanical television need not have been a technical cul-de-sac, and that in Britain at least, it was the political desire to maintain and extend the monopoly of the BBC, which effectively funnelled the technology into the model so familiar to us today.