Efforts towards internationalization have become increasingly important in scientific environments. As for content-based indexing of scientific research data, however, standards leading to internationally coherent indexing which is vital for retrieval purposes are not yet sufficiently developed. Even concerning the concrete use of indexing instruments, launched by initiatives on an international scale, there are still no binding policies and guidelines.
Against this backdrop, essential criteria which internationally applicable indexing systems should meet will be outlined. These will be illustrated through the multilingual European Language Social Science Thesaurus (ELSST ), originally based on the UK Data Archive’s (UKDA) Humanities and Social Science Electronic Thesaurus (HASSET ) and ultimately developed by the Council of European Social Science Data Archives (CESSDA). Additionally, the general pros and cons of using international versus national indexing languages will be weighed using the ELSST and the Thesaurus for the Social Sciences (TSS) developed by GESIS – Leibniz-Institute for the Social Sciences. In this light, the benefit of vocabulary crosswalks for supporting a combined use of international and national indexing systems will be discussed.