Many Americans engage in the habitual use of smokeless tobacco (ST) and wish to quit but lack the resources. There is a need for innovative, validated, and easily-delivered low cost interventions to help ST users quit using tobacco. This project takes advantage of the opportunity to study two tobacco cessation interventions that are growing in use but still need more systematic evaluation: (1) The use of the Internet for health information and tobacco cessation has been growing in popularity, and our recently-completed study (Chewfree.com) demonstrated the efficacy of a Web-delivered ST cessation program; (2) Tobacco quitlines are now available in all 50 states and have demonstrated promising results in empirical studies with smokers, and they are widely used by ST users. We propose to build on the work of two complementary and well- established research teams at ORI and UCSD to test the effectiveness of combining an interactive Web-based intervention with a quitline that provides telephone counseling for ST cessation. We plan to use a 2x2 design and 2,440 participants to test for the individual main effects of the Web program and phone counseling as well as to examine the added value when these treatment approaches are combined. Outcome measures include prolonged abstinence over a 6-month follow-up period. In addition to the tobacco cessation outcomes we will assess mediational processes through which each intervention condition may affect tobacco abstinence. We will also perform an economic analysis to evaluate the relative cost-effectiveness of offering these programs. This will be the first study to assess the efficacy of telephone helpline counseling for smokeless tobacco (snuff and chewing tobacco) cessation and also the first to test the relative value of adding Web-assisted cessation to a telephone quitline. Because of their broad reach, relatively low cost per user, and their promising results in empirical studies, both telephone counseling quitlines and Web-based interventions are emerging as important public health interventions for tobacco cessation. To date there has not been a test of these approaches when targeted to smokeless tobacco users. By seeking to answer questions about the individual and combined effectiveness of these promising approaches, and assessing the relative cost of delivering these programs, the proposed randomized controlled trial will help define best practices for ST cessation and could maximize the public health benefits of their use. [unreadable] [unreadable] [unreadable]