Research on mild traumatic brain injury (mTBI) has grown over recent years, though many gaps in knowledge still exist. One major gap is highlighted by the ambiguous diagnostic features that define mTBI. The current study systematically reviewed and extracted data from 124 studies to provide an overview of current mTBI research that has clinical relevance for assessing patients with mTBI. Results suggest that most mTBI research involves adult male samples, with major gaps in research on individuals less than 18 years old and who identify as female. Additionally, very few studies included individuals within the acute stages of mTBI recovery and more than half of the studies either did not report the racial composition of their sample or the majority of the sample was composed of White individuals. Additionally, cognitive assessment methods across mTBI research studies were examined to determine the most frequently assessed cognitive domains as well as the most frequently used cognitive assessment tools. This information was subsequently integrated to create a clinical decision-making guide for mTBI assessment practices. Results highlight major gaps in mTBI research and thus probable gaps in current understanding of how mTBI patients can present clinically. Additionally, findings provide a mTBI assessment guide, which can assist in the creation of uniform assessment and diagnostic practices.What is the significance of this article for the general public?This systematic review revealed gaps in research, which suggest more research is needed to examine individuals in the acute stages of mTBI recovery and that more representative research samples are needed with respect to race, age, sex, and gender. Additionally, a decision-making matrix was created as a guide for health care providers, researchers, and other general and professional audiences to recognize the appropriate approaches to performing a cognitive assessment for individuals who have experienced a mTBI.