BCPy2000 Jeremy Hill, Max-Planck-Institute for Biological Cybernetics, T¨ ubingen, Germany BCPy2000 provides a platform for rapid, flexible development of experimental Brain-Computer Interface systems based on the BCI2000.org project. From the developer’s point of view, the implementation is carried out in Python, taking advantage of various high-level packages: VisionEgg for stimulus presentation, NumPy and SciPy for signal processing and classification, and IPython for interactive debugging. BCPy2000 implements a lot of infrastructure allowing you to get new experiments up and running quickly. It also contains a set of optional tools, which are still a work in progress but which are rapidly turning into a kind of “standard library” of object-oriented signal-processing and stimulus widgets. These features make it a flexible platform for developers of new NumPy/SciPy-based machine-learning algorithms in the field of realtime biosignal analysis.