Unintended pregnancies occur among young people who are sexually active and who do not take sufficient precautions to prevent pregnancy. Two major factors identified as contributing to unintended pregnancy are the lack of knowledge and skill in family planning and inconsistency in use of contraceptives. A pretest-posttest experiment was conducted to determine whether nurse-client contracting was useful in counseling single, sexually active youth regarding prevention of pregnancy. Eighteen- to 22-year-old women (N=152) were randomly assigned to one of three groups: (1) routine clinic care only; (2) routine clinic care, education, and contracting; or (3) routine clinic care, education, contracting, and client-selected reinforcers for fulfilling contracts. Subjects completed questionnaires on knowledge about family planning and reported their reproductive history, frequency of intercourse, contraception, contraceptive use, communication with sex partner about birth control, and demographics. Analyses of data revealed a statistically significant increase in knowledge about human fertility, reproduction, and contraception for both contracting groups but not for the control group. Consistency in use of contraceptives also increased significantly for both contracting groups but not for the control group. Subjects in the contracting-without-reinforcement group had higher attrition rates than subjects in the other groups. These findings suggest that family planning nurse-client contracting, a form of client-centered nursing care, can positively influence the family planning knowledge and behavior of sexually active young women. (NB)