BACKGROUND: Depression is common after stroke and is associated with increased mortality. However, there are few data on the prevalence, predictors, or prognosis of depression after transient ischemic attack (TIA). Although poststroke depression is often assumed to be due to the brain lesion or disability, patients with TIA may also be susceptible due to shared risk factors, lifestyle/medication changes, or worries about stroke. METHODS: The prevalence of depression 1 and 12 months after TIA was assessed in a population-based cohort (OXVASC [Oxford Vascular Study]) from 2014 to 2020. Depression was related to risk factors (including infarction on brain imaging) in a multivariable logistic regression model and outcome (disability, quality of life, institutionalization, recurrent events, and mortality) in a Cox proportional hazard regression model during 5-year follow-up after adjustment for covariates that were found to be significant ( P <0.1) in the age-/sex-adjusted models. RESULTS: Of 519 patients (mean age, 70.5 [13.1]; female, 51.1%), 126 (24.3%) had depression after TIA, with a higher rate at 1 versus 12 months (99/20.7% versus 66/14.9%; P =0.022). Depression was independently associated with younger age (adjusted odds ratio/decade, 0.74 [95% CI, 0.60–0.90]), low baseline mood (4.06 [95% CI, 2.31–7.15]), past depression (1.81 [95% CI, 1.09–3.03]), multimorbidity (1.19 [95% CI, 1.02–1.39]), living alone (1.94 [95% CI, 1.14–3.32]), disability (3.53 [95% CI, 1.89–6.59]), and deprivation (1.28 [95% CI, 1.03–1.59]). After adjustment for confounders, depression did not predict risk of recurrent vascular events (adjusted hazard ratio [aHR], 1.42 [95% CI, 0.76–2.64]; P =0.27) but did predict increased 5-year all-cause mortality (aHR, 2.27 [95% CI, 1.21–4.27]; P =0.011), independently of acute lesions on brain imaging (aHR, 2.18 [95% CI, 1.09–4.34]; P =0.027), and particularly when persistent (present at 1- and 12-month follow-up; aHR, 4.58 [95% CI, 2.07–10.13]; P <0.001). Persistent depression was also independently associated with disability (adjusted odds ratio, 12.10 [95% CI, 6.18–23.7]; P <0.001) and institutionalization (aHR, 5.83 [95% CI, 1.84–18.50]; P =0.003) within 5 years and with reduced quality of life (coefficient, −0.245; P <0.001). CONCLUSIONS: Depression is common early after TIA, independent of acute ischemia on brain imaging, and persistent depression is also strongly associated with adverse outcomes.