Multilingual thesauri provide the context for exploring experimental user interfaces that support interactive visualization. The authors created two search interfaces that draw on the semantic richness of bilingual thesauri and provide for search, browse and results display. The Searchling interface offers search, browsable navigation and the full term-record data for a selected term, as well as a simple switch between language views. It provides active user assistance by displaying options to broaden or narrow search. User evaluation showed Searchling to be easy to use, appealing broadly but especially to linear thinkers. The T-Saurus interface is more visual, with term search results represented by the size, number, proximity and opacity of buckets. Terms can be displayed in multiple languages simultaneously, and multiple terms can be chosen to form a query to retrieve documents. Visual thinkers appreciated its dynamic and interactive visualization interface. Studies demonstrate the support both interfaces provide for fully using rich, multilingual thesauri as well as differences for users with different cognitive styles.