Restricted environmental stimulation therapy (REST) has been shown in several studies to be an effective technique in smoking intervention. The most common procedure has been 24 hours in a dark, silent chamber; in several cases, messages designed to facilitate smoking cessation have been presented every few hours over an intercom. This study parametrically varied 12 versus 24 hour chamber REST sessions and four message presentation schedules (massed, distributed, or self-demand presentation of five messages, and a no message condition). A ninth group of volunteer subjects spent five one hour sessions in a flotation REST tank. In this condition, no message was presented during the first session; one message was given during each of the next three sessions; and two messages were given in the last session. Previous findings of therapeutic efficacy were confirmed for chamber REST, with 3- and 12-month follow-ups showing means of 51% and 35% reduction, and 34% and 21% abstinence, respectively. The 24-hour distributed message group, representing the modal technique, showed a mean reduction rate of 51% and an abstinence rate of 36% one year after treatment. There were no significant differences as a function of the two main factors nor the interaction. Most chamber REST groups showed significant smoking reductions on both follow-ups. Flotation REST led to a significant decrease three months after the treatment, but not at one year. The data have theoretical as well as practical implications for future uses of REST.