According to "Blackdrags View" (http://blackdragsview.blogspot.com/2007_10_01_archive.html) the following enum definition should be possible in Groovy as of rc-1: enum E { A(100),B(200),C(300) def value E (v) { value = v } } When I try this in GroovyConsole, I get a puzzling MultipleCompilationErrorsException: Exception thrown: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, General error during conversion: org.codehaus.groovy.ast.expr.ConstantExpression cannot be cast to org.codehaus.groovy.ast.expr.ListExpression I'm not sure if this is really a compilation error or if it's only a misleading message because this kind of enum might not be actually supported.