Objectives. Lazarus and Folkman's (1984) stress appraisal model, widely applied in the depression literature, was uniquely applied in an expanded peritraumatic model to predict post traumatic stress disorder (PTSD) symptoms. The presented Transactional Vulnerability Model of Psychological Distress utilizes two of the most proximal determinants of PTSD symptoms identified in the stress and coping literature, peritraumatic appraisal and self-efficacy, as variables implicitly and explicitly identified in Lazarus and Folkman's (1984) primary and secondary appraisal processes. Study design. Correlational. Participants. Participants were multiple trauma, burn and orthopedic hand injured English-speaking adults who participated in Victorson's (2003) original psychometric validation study of the Traumatic Physical Injury and Psychosocial Stress Inventory (TIPSI; N = 169). Setting. Level 1 trauma center. Measures. Selected TIPSI subscales; General Perceived Self-Efficacy Scale; Abbreviated Injury Scale; Stressful Life Experiences Screening—Short. Results. The following variables were each significantly positively related to PTSD symptoms: prior trauma (r = .272); abuse-related prior trauma (r = .187); injury severity (r = .220); and each peritraumatic primary appraisal variable: threat potential (r = .431), controllability (r = .360), predictability (r = .238), meaningfulness (r = .397), stability of impact (r = .522) and globality of impact (r = .443). Each peritraumatic secondary appraisal variable was significantly inversely related to PTSD symptoms: general self-efficacy (r = -.501) and specific self-efficacy (r = -.272). Peritraumatic primary appraisal variables together explained 40.1% of variance in PTSD symptoms (F (2, 164) = 56.503, p < .001). The Transactional Vulnerability Model of Psychological Distress examined each aforementioned construct using mostly Victorson's (2003) measures in linear regression procedures in Model A (N = 161), explaining 45.1% variance in PTSD symptoms (F (11, 149) = 12.965, p < .001); Model B (N = 66) utilized two alternate measures and explained 52.9% variance ( F (10, 55) = 8.289, p < .001). These results support prior trauma and threat potential as predictors of PTSD symptoms and bespeak the importance of attributions of stability of impact and self-efficacy as proximal predictors of PTSD symptoms within an expanded Lazarus and Folkman stress appraisal model. Implications for early intervention among targeted individuals are discussed.