The literature related to people with borderline intellectual functioning (BIF) was systematically reviewed in order to summarize the present knowledge. Database searches yielded 1,726 citations, and 49 studies were included in the review. People with BIF face a variety of hardships in life, including neurocognitive, social, and mental health problems. When adults with BIF were compared with the general population, they held lower-skilled jobs and earned less money. Although some risk factors (e.g., low birth weight) and preventive factors (e.g., education) were reported, they were not specific to BIF. The review finds that, despite the obvious everyday problems, BIF is almost invisible in the field of research. More research, societal discussion, and flexible support systems are needed.