The objective of this study is to further the understanding of factors which may play a significant role in reducing the current levels of smoking among pregnant adolescents. This study will focus on developing, and systematically applying, interventions aimed primarily at smoking cessation by the target population. For this study, an adolescent is defined as any female who has not reached her 19th birthday before the estimated date of delivery. The potential study population will be composed of approximately 1100 pregnant adolescents less than 18 who each year use the Maternal and Infant Care Services at eight health clinics of the Jefferson county Health Department. The number identified at risk (smokers) is estimated to be 80 percent of approximately 880 at the two control sites per year. The interventions will be implemented and evaluated over a 3-year period consisting of 4 phases. During Phase 1, an epidemiologic profile and behavioral diagnosis will be performed to characterize study participants. Two major interventions will be selectively applied to adolescents identified as smokers at two intervention sites. A one-to-one intervention (S1) will be systematically applied to a group of randomly assigned patients during Phases 2 and 3. A peer-led group intervention (S2) will be applied in combination with X1 in Phases 2 and 3 to another randomly assigned group. A randomized experimental design will be utilized to evaluate the proposed smoking cessation project. Clinical and behavioral report data will be collected on clinic entry and during the last month of pregnancy of all adolescents in the program. A serum thiocyanata test (SCN) will be used to confirm the smoking behavioral reports. Using these methods and design, specific changes and differences in smoking behavior over time among the study groups will be established.