Purpose: The study aim was to develop a measure of self-reported quality of life (QoL) for people with mild to moderate dementia based on their views--the Bath Assessment of Subjective Quality of Life in Dementia (BASQID). Design and Methods: We developed the measure through multiple stages. Two field tests of the measure (ns = 60 and 150) enrolled people with dementia from a memory clinic, and we used the data to analyze the psychometric properties of the scale. Nested within this was a longitudinal investigation of 36 Alzheimer's disease patients prescribed with acetylcholinesterase inhibitors. Results: The BASQID contains 14 items assessing a range of QoL issues. Results showed that the BASQID satisfies the criteria of a valid, reliable, and acceptable assessment of subjective QoL. Scores were responsive to changes in QoL over 3 months. Low association between the BASQID and the Mini-Mental State Examination indicates that cognitive function may influence QoL but is an indirect measure of the QoL experienced during dementia. Implications: The BASQID provides a means of better understanding the experiences, perceptions, and beliefs of people with dementia. It does this through acknowledgement of the many influences on QoL over and above health status. Practitioners and researchers can use the BASQID alongside objective assessments of dementia to obtain a complete appraisal of a person's QoL. (Contains 2 footnotes, 4 tables, and 1 figure.)