Family Matters is a family-directed program to prevent adolescents 12 to 14 years of age from using tobacco and alcohol. The intervention is designed to influence population-level prevalence and can be implemented with large numbers of geographically dispersed families. The program encourages communication among family members and focuses on general family characteristics (e.g., supervision and communication skills) and substance-specific characteristics (e.g., family rules for tobacco and alcohol use and media/peer influences). The program involves successive mailings of four booklets to families and telephone discussions between the parent and health educators. Two weeks after family members read a booklet and carry out activities intended to reinforce its content, a health educator contacts a parent by telephone. A new booklet is mailed when the health educator determines that the prior booklet has been completed.