Objectives: To evaluate whether objectively and subjectively measured sleep disturbances persist among older adults in assisted living facilities (ALFs) and to identify predictors of sleep disturbance in this setting. Design: Prospective, observational cohort study. Setting and Participants: A total of 121 residents, age >= 65 years, in 18 ALFs in the Los Angeles area. Measurements: Objective (actigraphy) and subjective (Pittsburgh Sleep Quality Index) sleep measures were collected at baseline and 3- and 6-month follow-up. Predictors of baseline sleep disturbance tested in bivariate analyses and multiple regression models included demographics, Mini-Mental State Examination score, number of comorbidities, nighttime sedating medication use, functional status (activities of daily living; instrumental activities of daily living), restless legs syndrome, and sleep apnea risk. Results: Objective and subjective sleep measures were similar at baseline and 3- and 6-month follow-up (objective nighttime total sleep [hours] 6.3, 6.5, and 6.4; objective nighttime percent sleep 77.2, 77.7, and 78.3; and Pittsburgh Sleep Quality Index total score 8.0, 7.8, and 7.7, respectively). The mean baseline nighttime percent sleep decreased by 2% for each additional unit increase in baseline comorbid conditions (measured as the number of conditions), and increased by 4.5% for each additional unit increase in baseline activities of daily living (measured as the number of activities of daily living), in a multiple regression model. Conclusions: In this study, we found that objectively and subjectively measured sleep disturbances are persistent among ALF residents and are related to a greater number of comorbidities and poorer functional status at baseline. Interventions are needed to improve sleep in this setting. (Am J Geriatr Psychiatry 2012; 20:485-493)