ABSTRACT Delirium is frequently precipitated by urinary tract infection (UTI), a condition that disproportionately affects older women and contributes to increased mortality, prolonged length of stay, and accelerated long-term cognitive decline. Existing treatments for delirium center largely on treatment of the precipitating cause, modification of environmental contributors, and avoidance of deliriogenic medications; however, do not address the underlying pathobiology of the condition. We have developed a novel mouse model of UTI-induced delirium and generated compelling preliminary data that demonstrate a potential role for exogenously administered 17β-estradiol in mitigating UTI-induced delirium. These findings may explain, at least in part, why older women, who after menopause have reduced levels of 17β-estradiol, are particularly susceptible to developing delirium. In this R21 application, we propose to use our novel mouse model of urinary tract infection- induced delirium, oophorectomized mice, state-of-the-art behavioral testing, and genetically modified mice to determine whether 17β-estradiol ameliorates the structural and functional phenotypes of delirium via the G protein-coupled estrogen receptor 1. Given the lack of evidence-based pharmacological treatments for delirium, the findings from this research could have widespread clinical implications, including providing novel pre-clinical justification for clinical trials using a short-term application of an existing drug, 17β-estradiol, to ameliorate UTI- induced delirium and quality of life for millions of older women around the world.