There are still relatively few spoken language dialogue systems around, so the literature on their evaluation is fairly thin. The following readings provide a good introduction to the state of the art: [Bailleul (1987)], [Bates et al. (1990)], [Bates & Ayuso (1991)], [Boogart et al. (1993)], [Cookson (1988)], [Delogu et al. (1993a)], [Gerbino et al. (1993)], [Goodine et al. (1992)], [Hirschman et al. (1990)], [House et al. (1992)], [Simpson & Fraser (1993)], [Smith et al. (1992)], [Tubach & Doignon (1991)], [Vergeynst et al. (1993)], and [Zue et al. (1991)].