The number of older prisoners is increasing exponentially. For example, the number of geriatric female prisoners in California has increased 350% in the past decade. Despite an increasing population of geriatric female prisoners, the degree of functional impairment in this population is unknown. Therefore, the goals of this study were to describe the prevalence and nature of functional impairment in geriatric female prisoners in California and to identify aspects of the prison environment that may exacerbate functional impairments. Questionnaires were analyzed from 120 geriatric women in California state prisons. Functional impairment was defined as impairment in activities of daily living (ADLs) or in prison ADLs (PADLs), including dropping to the floor for alarms, standing for count, getting to meals, hearing orders, and climbing onto the top bunk. The mean age of participants was 62; 16% were dependent in one ADL, and 69% reported one PADL impairment. Increasing severity of functional impairment was associated with worse health status and more adverse prison experiences. For example, fall rates ranged from 33% in women without impairment to 57% with PADL impairment to 63% with ADL dependence (P=.02). Several prison environmental stressors were identified that likely exacerbate functional impairment. For example, 29% of geriatric women were assigned to a top bunk. Geriatric female prisoners report high rates of functional impairment. ADL and PADL impairment were associated with worse health status and adverse prison experiences. Therefore, the evaluation of functional impairment in geriatric female prisoners needs to consider the unique demands of the prison environment.