OBJECTIVE: To evaluate the efficacy of Simulated Presence, a personalized approach to enhance well-being among nursing home residents with Alzheimer's disease and related dementia's (ADRD). DESIGN: Latin-Square, double blinded, 3-factor design with restrictive randomization of three treatments (the study intervention, a placebo audio tape of a person reading the newspaper, and usual care). The three factors were treatment, time, and facility type. SETTING: Nine nursing homes in Eastern Massachusetts and Southern New Hampshire. PARTICIPANTS: Fifty-four subjects with documented ADRD who were aged 50 years or older, medically stable, had resided in their current nursing home for at least 3 months, and who had no planned discharge. All subjects had a history of agitated or withdrawn behaviors. INTERVENTION: The purpose of Simulated Presence is to provide a personalized intervention for persons with moderate to severe cognitive impairment. Through a unique testing process, some of the best loved memories of the ADRD person's lifetime are identified and then those memories are introduced to the patient in the format of a telephone conversation using a continuous play audio tape system. The intervention may be used for extended periods of time because each repetition is viewed as a fresh, live telephone call as a result of the short-term memory deficit of the person with ADRD. MEASUREMENTS: Direct observations of outcomes included using a newly developed scale, the Scale for the Observation of Agitation in Persons with Dementia, an agitation visual analog scale, the Positive Affect Rating Scale (mood and "interest"), a withdrawal visual analog scale, and facial diagrams of mood. Reported measures included daily staff observation logs of responses to interventions offered, and weekly staff surveys using the short-form Cohen-Mansfield Agitation Inventory and the Multidimensional Observation Scale for Elderly Subjects (mood and "interest"). Severity of dementia was assessed by the Mini-Mental State Exam, the Test for Severe Impairment, the Bedford Alzheimer's Nursing Scale, and the ADL Self-Performance Scale. RESULTS: Chi-square analysis of direct observations, using facial diagrams, revealed that Simulated Presence was equivalent to usual care (P =.141) and superior to placebo for producing a happy facial expression (P =.001). A positive effect was also documented in nursing staff observation logs using Analysis of Variance techniques (ANOVA) for subjects during Simulated Presence phases compared with the placebo phases (P <.001) and usual care phases (P <.001). According to ANOVA analyses of "interest" from weekly surveys, Simulated Presence was superior to both usual care (P =.001) and placebo (P =.008). We were unable to find evidence of significant differences (P <.05) among interventions for other direct observations and weekly reports of overall agitation or mood aspects of withdrawal. Subjects accepted the intervention most of the time, except for five subjects who refused it more than 50% of the time. CONCLUSION: This study provided evidence that Simulated Presence can be effective in enhancing well-being and decreasing problem behaviors in the nursing home setting as a substitute for or complement to usual care.