Well, I could not found any tutorial about this on the net. It would be very kind from you to give me a link if you have one ;) I just found tutorials for custom EL functions used in JSP via taglibs. But my app uses facelets, not JSP. Moreover the EL expression to evaluate is in a resource bundle, which is a Seam EL enhancement for what I understood. I had a look on the way this has been done for s:hasRole and s:hasPermission built-in Seam EL functions, but it looks like this has been hard-coded in org.jboss.seam.el.SeamFunctionMapper class. Do you know an easy way to add my own EL functions to this Seam function mapper, in a configuration file for example ? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4111236#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...