Beyond Einstein science is a term that applies to a set of new scientific challenges at the intersection of physics and astrophysics. Observations of the cosmos now have the potential to extend our basic physical laws beyond where 20th-century research left them. Such observations can provide stringent new tests of Einstein's general theory of relativity, indicate how to extend the Standard Model of elementary-particle physics, and -- if direct measurements of gravitational waves were to be made -- give astrophysics an entirely new way of observing the universe. In 2003, NASA, working with the astronomy and astrophysics communities, prepared a research roadmap entitled Beyond Einstein: From the Big Bang to Black Holes. This roadmap proposed that NASA undertake space missions in five areas in order to study dark energy, black holes, gravitational radiation, and the inflation of the early universe, to test Einstein's theory of gravitation. This study assesses the five proposed Beyond Einstein mission areas to determine potential scientific impact and technical readiness. Each mission is explored in great detail to aid decisions by NASA regarding both the ordering of the remaining missions and the investment strategy for future technology development within the Beyond Einstein Program.