Abstract. In this paper we present the logic-programming language XCentric, discuss design issues, and show its adequacy for XML processing. Distinctive features of XCentric are a powerful unification algorithm for terms with functors of arbitrary arity (which correspond closely to XML documents) and a very rich type language that uses operators such as repetition (*), alternation, etc, as types allowing a compact representation of terms with functors with an arbitrary number of arguments (closely related to standard type languages for XML). This non-standard unification together with an appropriate use of types yields a substantial degree of flexibility in programming. 1