Prenatal care providers can play an important role in identifying, intervening in, and making referrals for substance abuse problems among pregnant women. Although studies suggest that most addicted persons who need treatment do not receive it, innovative methods such as the one described here can help increase the number of pregnant women who engage in treatment, with likely benefits to the client, her unborn baby, and other children whom she may parent. A qualitative study of the implementation of an innovative model to prevent and treat substance abuse among pregnant women is presented. The study took place in a prenatal clinic staffed by nurse-midwives in a dense suburb serving a population largely covered by Medical Assistance. Results indicate that education, training, and structural changes in care delivery led to changes in the attitudes and behaviors of nurse-midwives toward pregnant addicted women and increased their effectiveness.