In this paper we propose a technique for evaluating similarity of XML Schema fragments. Firstly, we define classes of structurally and semantically equivalent XSD constructs. Then we propose a similarity measure that is based on the idea of edit distance utilized to XSD constructs and enables one to involve various additional similarity aspects. In particular, we exploit the equivalence classes and semantic similarity of element/attribute names. Using experiments we show the behavior and advantages of the proposal. Categories and Subject Descriptors I.7.1 [Document and Text Processing]: Document and Text Editing