The belief that schools can play a powerful role in preventing tobacco use among adolescents has led to the implementation of various tobacco-related polices and practices. This study examines the association between school policies regarding monitoring student behavior, severity of action taken for infraction of policies, and tobacco use by staff, and student smoking behavior and attitudes. Data on students' smoking behavior and attitudes were obtained from the 1999 and 2000 Monitoring the Future surveys of nationally representative samples of 8th-, 10th-, and 12th-grade students. Data on school policies and practices were obtained from administrators in those same schools. Hierarchical analyses using HLM5 were conducted. Strictness of monitoring was significantly negatively associated with daily cigarette use by middle school students. Permitting staff to smoke was significantly positively associated with students' daily cigarette use and negatively with their disapproval of cigarette use. Policy implications are discussed. (Contains 3 tables.)