I solved my problem. Here's a synopsis of the winning configuration: 1. Configured JBoss via the ant script in "jbossws-native-2.0.0". Ended up with the following in "$JBOSS_HOME/lib/endorsed": - jaxb-api.jar - jboss-jaxrpc.jar - jboss-jaxws.jar - jboss-saaj.jar - serializer.jar - xalan.jar - xercesImpl.jar 2. Added the same files to "$JAVA_HOME/jre/lib/endorsed", which allowed my standalone web service client to work. Note that I tried every permutation of "endorsed" directories and "java.endorsed.dirs" settings and this is the ONLY configuration that worked. Larry View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4188924#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...