When I run a servlet that takes in an XML and XSL file and performs the XSLT before outputting to a browser, I get the following error: java.lang.NoClassDefFoundError: javax/xml/transform/Source I have the jar file with the javax stuff in my classpath, but the import just isn't working: import javax.xml.transform.*; import javax.xml.transform.dom.*; import javax.xml.transform.sax.*; import javax.xml.transform.stream.*; No problems on compile. Any ideas?