If I've the simple classes: public class ObjectBar{ public String name; gets/sets} public class ObjectFoo{ public ObjectBar bar; gets/sets } ... and ObjectFoo this in WorkingMemory. It's not possible navigate in objectFoo for make constraint in objectBar? Example: rule "Teste" no-loop true when $foo: ObjectFoo(objectBar.name != "foobar") then System.out.println($foo); end ... but: org.drools.RuntimeDroolsException: Exception executing predicate org.drools.base.mvel.MVELPredicateExpression@18488ef Caused by: org.mvel.CompileException: unable to resolve property: nome Caused by: org.mvel.PropertyAccessException: unable to resolve property: nome Thanks Alessandro Lazarotti