The results indicate that the frequency of adolescent cannabis use is independently related to adolescent cognitive functioning. Specifically, adolescents who reported regular cannabis use performed significantly poorer than the other adolescents on measures of cognitive functioning related to attention, spatial working memory, and learning. After controlling for other relevant variables, cannabis remained an independent predictor of working memory and strategy performance. The findings have implications for the memory of adolescents who regularly use cannabis and for their performance in school. Future research should consider following a group of adolescent regular cannabis users over time to investigate their cognitive functioning before and after cessation or reduction of cannabis use. Participants were 70 adolescents recruited from clinical and community centers and through newspaper advertisements. Adolescents were asked to abstain from cannabis use for 12 hours, after which they completed a 2-hour interview that focused on demographic information, alcohol and drug use history, drug use during the past 28 days, depression, other psychiatric functioning, and cognitive functioning. Cognitive functioning was measured using computerized tasks and traditional pen and paper tests. Tables, references