In this review, we analyzed literature related to the clinical, theoretical, and empirical determinants of mild traumatic brain injury (MTBI) in adults, with a focus on outcomes. Consequences after MTBI were summarized, patient outcomes were organized following Ferrans and Powers' conceptual model of quality of life, and gaps in knowledge were identified. The following databases were searched for publications related to MTBI: PubMed, PsycINFO, CINAHL, and Digital Dissertation. A total of 44 publications related to MTBI in adults were identified. Neither clinical nor theoretical definitions nor empirical descriptions agreed on the determinants of MTBI in adults. Nine reports included a holistic evaluation of outcomes after MTBI; an additional 35 studies examined health and functioning, psychological, or socioeconomic consequences. Results were mixed regarding how MTBI affects individuals in overall quality of life and which domains of quality of life are affected. With more than one million adults experiencing MTBI annually in the United States, it benefits the healthcare professional to understand the challenges of identifying adults who experience MTBI. Furthermore, the consequences of MTBI may be clinically important. Further research about MTBI using clear definitions and a holistic approach to recovery is warranted.