We present SchemaScope, a system to derive Document Type Definitions and XML Schemas from corpora of sample XML documents. Tools are provided to visualize, clean, and refine existing or inferred schemas. A number of use cases illustrates the versatility of the system, as well as various types of applications. Categories and Subject Descriptors I.7.2 [Document and Text Processing]: Document Preparation; F.4.3 [Mathematical Logic and Formal Languages]: Formal Languages; I.2.6 [Artificial Intelligence]: Learning General Terms Algorithms, Languages, Theory Keywords XML, regular expressions, schema inference