 Potential reduced exposure products PREPs are being developed and marketed by the tobacco industry in an attempt to reduce some of the risks involved in tobacco use see Breland et al., 2002b. Evaluating the effects of these products is crucial to public health, as past industry-sponsored efforts at harm reduction e.g., so-called light and ultra-light cigarettes were not evaluated and failed to reduce carbon monoxide CO, nicotine, and carcinogen exposure in smokers; these efforts thus failed to reduce the harms of smoking Stratton et al., 2001. This study is part of an on-going, NIH-funded program of research to develop a science-based model that uses outcome measures relevant to evaluating current tobacco industry-sponsored smoking harm reduction efforts systematically and efficiently. 