The purpose of the article is to accomplish several complementary research tasks. First, the issue of sources of the content of conventional acts in law is discussed. Then, detailed issues regarding the content of conventional acts in law are presented against the background of dogmatic and legal reflections as well as problems related to the identification of conventional acts. Additionally, the author makes an attempt to determine the ways of understanding ‘the content (of conventional acts in law)’ in particular legal sciences. The research results presented in the article (apart from their cognitive value) are supposed to serve the development of the general theoretical concept of conventional acts in law, as well as to organise the dogmatic and legal discussion on the titular issue as much as possible.