This paper presents an experimental approach of using crowdsourcing to test controlled vocabularies for digital collections of cultural objects. For a digital humanities initiative project, Project Andvari, which is intended to create a digital portal of early medieval northern European artifacts, it was recognized that there was a need to develop a semantically structured iconographic thesaurus to describe the iconographic content of distributed artefactual collections from a variety of contributing institutions. This paper discusses a workflow of planning and development process of controlled vocabularies for the project and a testing process of the vocabularies to determine both the usability of controlled vocabularies and the feasibility of quality assurance approach. This paper demonstrates an applicability of crowdsourcing in developing controlled vocabularies.