Thomason had a great interest on learning how to do fieldwork about Indo-European languages. She decided that Indo-European languages from Eastern Europe would be best suited for research as Western European languages had been already thoroughly studied and the literature was vast. She traveled to the former Yugoslavia and started preparing her project on Serbo-Croatian, with the intention of focusing her career on Slavic studies. Thomason would spend a year in this region writing her dissertation project on noun suffixation in Serbo-Croatian dialectology. Thomason would not, however, continue focusing neither on Slavic nor on Indo-European languages.