The physical environment has been increasingly recognised as an important therapeutic tool in dementia care. This study was designed to demonstrate the positive impact that environmental interventions can have on people with dementia. The present study involved designing implementing an simple and cost effective intervention in the living areas of dementia care homes, by re-arranging the existing furniture in the room. The research was based on the theoretical background of Lawton’s Environmental Docility hypothesis (1979) and the Behaviour Constraint Model of the environment-behaviour relationship (Proshanky et al., 1970). From these theories a number of principles were developed to inform the intervention. The intervention was designed to increase the choice of areas in the room and affordances for different activities, as well as providing visual access to nature with views from the window. Based on these principles an intervention was put in place in 7 living areas across three dementia care homes. A behaviour mapping methodology was employed to assess the behaviour of the residents pre and post intervention. Following the intervention in each care home, a focus group or interview was conducted with care home staff to explore understanding of the environment-behaviour relationship, their perceptions of the intervention in the care home and their understanding of the impact on the residents. The results demonstrate positive changes in behaviour post intervention, including an increase in active behaviours and a decrease in agitation. Staff views of the intervention and their knowledge of the environment-behaviour relationship differed between care homes. This has been placed in context of supporting information from other sources (e.g. the Care Commission) which showed that staff who worked in care homes which were rated poorer on aspects of the environment had a deeper understanding of the importance of the environment, viewed the intervention more positively and were more likely to comment on a change in the behaviour of residents, for example noticing an increase in positive social interactions between residents. The staff perceptions of the intervention will be discussed alongside the objective behaviour observations of the residents. These results will be framed in terms of implications for integrating the use of environmental interventions with existing policies in dementia care.