A 1998 study from the National Center on Addiction and Substance Abuse (CASA) found that teens from families that eat dinner together regularly were a whopping 31% less likely to abuse drugs. And adolescents from families that never ate dinner together were 72% more likely to engage in substance abuse activities. In another 1994 study, Lou Harris and Associates surveyed 2000 high school seniors, and found that students who ate dinner with their families regularly (4 or more times a week) scored better on a battery of academic tests.
from:
http://www.pittsburghboomers.com/Archive/08Aug03/080308Dinner.htm