||Impulsivity is hypothesized to underlie numerous cognitive, social, and clinical deficits. Although there are several theories suggesting that dim lighting is related to an increase in impulsivity, empirical studies have yet to demonstrate a conclusive time order relationship. The present study put 72 participants into either a brightly or a dimly lit lab setting and asked them to complete the Stop Signal Reaction Time task (Logan, Schachar, & Tannock, 1997). Following this, the BIS-11 (Barratt, 1994) was administered under normal lighting in order to determine whether dim artificial illumination affects those with an impulsive personality differentially. Students in the dim light condition did not perform significantly slower on the reaction time task, however, the data indicate the desired results may be better captured with a self-report impulsivity measure. Implications and suggestions for future research are discussed.