Background: Mild traumatic brain injury (MTBI) is a stressful life event that may impact various dimensions of life. Challenges to daily activities after MTBI may produce significant effects on quality of life (QOL). Purpose: The purposes of this cross-sectional descriptive study were to (a) explore QOL after experiencing MTBI, (b) determine the extent of social supports, and (c) identify factors that are associated with QOL in post-MTBI patients. Methods: A descriptive research method was used. Potential subjects were interviewed by telephone after they signed the consent forms. Results: The average score of total social support was 73, the average availability subscale score was 40, and the average satisfaction subscale score was 33. The average score of total QOL was 24, the average health and functioning domain score was 22, the average psychological and spiritual domain score was 25, the average social and economic domain score was 25, and the average family domain score was 27. QOL was then regressed simultaneously on all factors after adjustment of the outliers. The model was supported (adjusted R2 = .246, F = 4.160, p G .001). The contribution of all the stimuli explained 24.6% of the variance in QOL (p G .0125). Social support was the most significant variable affecting the variance in QOL (the unstandardized regression coefficient = 1.105, the standardized regression coefficient = 0.414, t = 5.041, p G .001). Conclusions: This study identified social support as the most powerful predictor for QOL. Several measures used in this study were reliable and may be used within the Thai cultural context. Further study to better understand why a small but clinically important percentage of subjects experience ongoing disability after MTBI is needed.