Which JBossAS 5.0? CR1? I assume that you verified that the JDBC driver JAR file you placed in server/default/lib actually contains the class com.microsoft.sqlserver.jdbc.SQLServerDriver. Also, avoid whitespace in XML file, much of the code that reads this stuff does not trimm leading or trailing whitespace. Change it to: <connection-url>jdbc:sqlserver://localhost;instanceName=SQL2005;portNumber=1433;databaseName=question;</connection-url> | <driver-class>com.microsoft.sqlserver.jdbc.SQLServerDriver</driver-class> View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4165733#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...