Open source projects do have requirements; they are, however, mostly informal, text descriptions found in requests, forums, and other correspondence. Understanding of such requirements can provide insight into the nature of open source projects. Unfortunately, manual analysis of natural language (NL) requirements is time-consuming, and for large projects, error-prone. Automated analysis of NL requirements, even partial, will be of great benefit. Towards that end, we describe the design and validation of an automated NL requirements classifier for open source projects. Initial results suggest that it can reduce the effort required to analyze requirements of open source projects.