Relativity was Einstein’s main research programme and scientific project. It was an open-ended programme that developed throughout Einstein’s scientific career, giving rise to special relativity (SR), general relativity (GR), and unified field theory. In this article, we want to uncover the methodological logic of the Einsteinian programme, which animated the whole programme and its development, and as it was revealed in SR, GR, and unified field theory. We aver that the same methodological logic animated all these theories as Einstein’s work (...) progressed. Each of these theories contributed towards constructing Einstein’s ambitious programme. This article is not a contribution to the history of relativity, but, rather, it utilises our knowledge of this history to uncover the methodological logic of the relativity programme and its development. This logic is latent in the historical narrative but is not identical to it. We hope to show that the Einsteinian relativity project is still relevant today as a theoretical scheme, despite its failures and despite quantum mechanics. (shrink)