Abstract. It can be difficult to automatically generate "nice" graphical representations for concept lattices from lexical databases, such as Roget's Thesaurus, because the data sources tend to be large and complex. This paper discusses a variety of "data weeding" techniques that can be applied in order to reduce the size of a concept lattice, first in general, and then with respect to Roget's Thesaurus. The aim is that resulting lattices should display neither too much, nor too little information, independently of which search terms have been entered by a user.