A review of observation tools to measure quality of life and well-being of people with dementia by Algar, Woods and Windle (2014) concluded that the Greater Cincinnati Chapter Well-Being Observation tool (GCCWBOT: Rentz, 2002; Kinney & Rentz, 2005) was the most appropriate tool for assessing psychosocial interventions such as art. Following this, observation data were collected in three conditions (a visual art programme; another structured activity; and unstructured time) in a care home with residents living with dementia and adaptations made to the tool (Algar, 2015). Dementia and Imagination is a three year study comparing the responses of people living with dementia attending a weekly programme of visual art engagement led by professional artists to group settings which did not involve art. The adapted version of the GCCWBOT was used to record the affect and engagement of ‘Dementia and Imagination’ group members within eleven groups (June 2104- September 2015) from three separate sites collecting data in a care home setting, hospital assessment ward, and a community setting. Face to face training in the GCCWBOT was delivered to the observers and tests to ensure all the observations were collected according to the same standards were conducted before and during the live observation data collection periods. In total 120 group members living with dementia were observed in a social group setting which did not involve any art activity before the twelve week art programme started. Observations were repeated within the first 3 sessions of the art programme and again during the last two sessions (weeks 11 and 12). Preliminary results of the inter-rater reliability between coders and changes over time for the complete observation data will be shared, along with a discussion about how to ensure observational measures are used effectively when evaluating a visual art programme with people living with dementia.