Vocabularies typically reflect a consensus among experts in a certain application domain. They are thus implemented in collaboration of domain experts and knowledge engineers. Particularly the presence of domain experts with little technical background requires a low-threshold vocabulary engineering methodology. This methodology should be im- plementable without dependencies on complex software components, it should provide collaborators with comprehensible feedback on syntax and semantics errors in a tight loop, and it should give access to a human- readable presentation of the vocabulary. Inspired by agile software and content development methodologies, we define the VoCol methodology to address these requirements. We implemented a prototype based on a loose coupling of validation and documentation generation components on top of a standard Git repository. All of these components, even the repository engine, can be exchanged with little effort. By evaluating the usefulness of error feedback of different tools in the realistic setting of an emerging mobility vocabulary we prove, however, that our choice of the crucial validation component is workable.