It was proposed that the lack of insight into the risk-taking behavior of many sexually active women who do not want to get pregnant may reflect the lack of an adequate framework from which to investigate the problem. The purpose of this study was to examine the relationships between contraceptive effectiveness and several cognitive factors. The sample consisted of 155 single women, 15.3-25.7 years of age, from a Planned Parenthood clinic and an abortion clinic. Contraceptive effectiveness, operationally defined as the number of unplanned pregnancies in a woman's history, was significantly and negatively related to means-ends problem-solving ability and a belief in internal control and significantly and positively related to a belief in chance control. It was suggested that these results support the utility of a cognitive, problem-solving approach to the study of contraceptive behavior.