This dissertation explores Ronald Reagan's historic 1986 summit with Mikhail Gorbachev in Reykjavik. Through the analysis of primary source documents from the Ronald Reagan Presidential Library and other sources I have excavated the intellectual origins of Reagan's atomic diplomacy, and sought to explain his fateful decision to cling to the Strategic Defense Initiative (SDI) in the face of Gorbachev's tantalizing offer to eliminate all strategic nuclear weapons over a 10-year time period. Ultimately, I argue that Reagan's faith in the transformative and innocent qualities of American military technology, and his belief in the providential destiny of the United States fueled his quest for strategic superiority, his vision of SDI, and his conduct at Reykjavik. I also consider many other factors which influenced Reagan's atomic diplomacy, including the exigencies of domestic and global politics, and the transnational nuclear freeze movement. I conclude that Reagan may have missed a grand opportunity to halt what he most dreaded: an arms race which now threatens to spiral out of control on earth and into the heavens.