South Africa and Kenya are among some nations that have adopted what are referred to as ‘transformative constitutions’, with the aim of bringing about radical change that would repair the cumulatively deep fissures in their societies. In order to determine how to satisfactorily give these constitutions effect, judges may undertake to first understand the people’s past experiences and how that informed the constitutional provisions that were adopted. This will in turn allow them to grasp what sort of transformation the people sought. One of the sources by which to undertake such a task is preparatory documents. In this study, these are the materials detailing the people’s views on the then-prospective constitutional provisions and discussions during constitutional conferences. By reference to the United States courts as a case study, this article seeks to find out the use to which judges interpreting provisions in the Constitution of Kenya and the Constitution of South Africa put preparatory documents. It does so through an empirical examination of select Human Rights decisions in both jurisdictions. It eventually finds that the examination of preparatory documents need not necessarily be viewed as an exercise that will restrain a judge, or fold back progress that has been made in progressive adjudication. At the very least, it will help a judge understand the transformation sought while in some cases, it may legitimize and enlighten a judge’s decision to interpret a provision in a more expansive manner.