This paper studies Bukharin's Theory and Practice from the Standpoint of Dialectical Materialism presented at the 2nd International Congress of the History of Science in London, June 29–July 3, 1931. Bukharin's paper has not received the attention it deserves despite the fact that it provides the theoretical framework for the paper mostly highlighted in this Congress, Boris Hessen's The Social and Economic Roots of Newton's Principia. In this work, I try to show that Bukharin's main achievement is a theory of science based on the concept of practice and at the same time present the internal coherence and the logical structure of Bukharin's schema. Finally, I discuss what, in my opinion, is a drawback in Bukharin's paper: his failure to discuss the possibility for scientific objectivity.