Abstract: I will discuss certain groups of homeomorphisms of compact manifolds which are called locally dense. This class of groups includes many natural examples, including piecewise linear homeomorphisms and diffeomorphisms groups, as well as Thompson’s groups F and T. I will discuss some of the model theory of these groups, and the implications their model theory has for finiteness properties of groups that are elementarily equivalent to locally dense groups. I will also discuss how one can recover a result of Laserre, which asserts that Thompson’s groups F and T are the unique finitely generated groups with their respective theories. This talk represents joint work with J. De la Nuez Gonzalez.