The past 15 years have seen a marked increase in the use of Snoezelen with a wide range of groups including people with intellectual disabilities. Research has been undertaken with respect to a variety of behaviors, notably changes in affect, challenging behavior, relaxation and interactions with both other persons and objects. Typically studies have adopted an applied behavior analysis approach, with a small number employing physiological measures. Research designs vary markedly in their technical adequacy and the participants have a wide range of intellectual disability, age, and additional characteristics such as autism. Much of the literature reviewed demonstrates a wide range of positive outcomes when Snoezelen Vs non-Snoezelen environments are contrasted, though there is little evidence of generalisation even to the immediate post-Snoezelen environment. Several studies, however, do yield entirely negative outcomes. It is difficult to attribute these differing outcomes to either participant characteristics or contrasted designs, given the diversity of approaches to evaluation and the relatively small number of studies. The review also addresses the issue of staff and carer attitudes and the place of Snoezelen in facilitating positive interactions, incidental to any specific sensory effects. Attention is drawn to the need to improve research designs in studying Snoezelen and to developing a clearer theoretical basis for use of this approach.