An intervention, termed 'Individualised Sensory Environment' (ISE), was developed for use with adults with profound and multiple learning disabilities (Bunning 1996). The aim was to affect positively the interactive behaviours displayed by clients in the natural environment: specifically; to reduce the level of non-purposeful engagement, characterised by stereotypic actions, self-injury and neutral behaviour and to increase the levels of purposeful interaction with people and objects. Momentary time sampling was the chosen method of assessment. The results showed that the clients emitted high levels of non-purposeful behaviour at baseline. Post ISE intervention assessment revealed a decline in the level of non-purposeful behaviour and an increase in purposeful interactions.