Objectives: The aim of the current study was to examine the relations among mindfulness, posttraumatic stress disorder (PTSD) symptom severity, and stressful life events (SLEs) in African-American urban adolescents. Another aim was to examine mindfulness as a moderator of the relation between SLEs and PTSD symptom severity in this population. Method: Eighty-eight African-American high school students from a low-income urban community completed measures of demographics, PTSD symptom severity, SLEs, and mindfulness. Results: Mindfulness was significantly negatively related to PTSD symptom severity, r(86) = −.70, p < .001, 95% CI [−.58, −79], and SLEs were significantly positively related to PTSD symptom severity, r(86) = .29, p = .003, 95% CI [.09, .47]. Mindfulness was an independent predictor of PTSD symptom severity after accounting for SLEs, B = −1.16, t(84) = −9.06, p < .001, 95% CI [−1.41, −0.90], and SLEs were an independent predictor of PTSD symptom severity after accounting for mindfulness, B = 0.49, t(84) = 2.92, p = .004, 95% CI [0.16, 0.82]. Mindfulness did not moderate the relation between SLEs and PTSD symptom severity, B = −.003, t(84) = −0.15, p = .89, 95% CI [−.04, .03]. Implications: This study has implications for both mindfulness as a potential protective factor against PTSD symptom severity and SLEs as a potential risk factor for increased PTSD symptom severity in African-American urban adolescents.