Python is a popular all-purpose scripting language, while R (an open source implementation of the S/Splus language) is a scripting language mostly popular for data analysis, statistics, and graphics. If you are reading this, there are good chances that you are at least familiar with one of both. Having an interface between both languages to benefit from the libraries of one language while working in the other appeared desirable; an early option to achieve it was the RSPython project, itself part of the Omegahat project. A bit later, the RPy project appeared and focused on providing simple and robust access to R from within Python, with the initial Unix-only releases quickly followed by Microsoft and MacOS compatible versions. This project is referred to as RPy-1.x in the rest of this document. The present documentation describes RPy2, an evolution of RPy-1.x. Naturally RPy2 is inspired by RPy, but also by A. Belopolskys’s contributions that were waiting to be included into RPy. This effort can be seen as a redesign and rewrite of the RPy package, and this unfortunately means there is not enough left in common to ensure compatibility.