Data were collected on the drinking behavior of 415 pregnant adolescents from 1990 to 1994. The relationships between knowledge and attitudes about drinking and drinking behavior were examined. Knowledge about drinking was not related to average daily volume of alcohol before or during pregnancy. Those with specific knowledge about fetal alcohol effects drank less before pregnancy, and in the first trimester, and were also less likely to drink to intoxication. Among drinkers, general knowledge about drinking was significantly related to a decrease in drinking between pre-pregnancy and first trimester, as well as between first and third trimesters. Those with more intolerant attitudes about drinking drank less before and during pregnancy. They had fewer episodes of binge drinking, intoxication, negative consequences, and problem drinking during pregnancy. They were more likely to decrease drinking from the first to third trimesters. These relationships are relevant to developing effective education programs for the high-risk group of pregnant teenagers who drink.