The high global burden of traumatic brain injury (TBI) disproportionately affects low- and middle-income countries (LMICs). These settings also have the greatest disparity in the availability of surgical care in general and neurosurgical care in particular. Recent focus has been placed on alleviating this surgical disparity. However, most capacity assessments are purely quantitative, and few focus on concomitantly assessing the complex healthcare system needs required to care for these patients. The objective of the present study was to use both quantitative and qualitative assessment data to establish a comprehensive approach to inform capacity-development initiatives for TBI care at two hospitals in an LMIC, Cambodia. This mixed-methods study used 3 quantitative assessment tools: the World Health Organization Personnel, Infrastructure, Procedures, Equipment, Supplies (WHO PIPES) checklist, the neurosurgery-specific PIPES (NeuroPIPES) checklist, and the Neurocritical Care (NCC) checklist at two hospitals in Phnom Penh, Cambodia. Descriptive statistics were obtained for quantitative results. Qualitative semistructured interviews of physicians, nurses, and healthcare administrators were conducted by a single interviewer. Responses were analyzed using a thematic content analysis approach and coded to allow categorization under the PIPES framework. Of 35 healthcare providers approached, 29 (82.9%) participated in the surveys, including 19 physicians (65.5%) and 10 nurses (34.5%). The majority had fewer than 5 years of experience (51.7%), were male (n = 26, 89.7%), and were younger than 40 years of age (n = 25, 86.2%). For both hospitals, WHO PIPES scores were lowest in the equipment category. However, using the NCC checklist, both hospitals scored higher in equipment (81.2% and 62.7%) and infrastructure (78.6% and 69.6%; hospital 1 and 2, respectively) categories and lowest in the training/continuing education category (41.7% and 33.3%, hospital 1 and 2, respectively). Using the PIPES framework, analysis of the qualitative data obtained from interviews revealed a need for continuing educational initiatives for staff, increased surgical and critical care supplies and equipment, and infrastructure development. The analysis further elucidated barriers to care, such as challenges with time availability for experienced providers to educate incoming healthcare professionals, issues surrounding prehospital care, maintenance of donated supplies, and patient poverty. This mixed-methods study identified areas in supplies, equipment, and educational/training initiatives as areas for capacity development for TBI care in an LMIC such as Cambodia. This first application of the NCC checklist in an LMIC setting demonstrated limitations in its use in this setting. Concomitant qualitative assessments provided insight into barriers otherwise undetected in quantitative assessments.