Lesbian, gay, and bisexual populations are at elevated risk for tobacco use compared to their heterosexual peers. However, there is little research examining reasons for this disparity. Drawing on prior literature regarding psychosocial variables associated with both sexual orientation and smoking, the authors tested a path model of risk and protective factors to help explain sexual orientation differences in smoking using data from the Washington State Behavioral Risk Factor Surveillance System from 2003 to 2007. The authors estimated separate models for men and women, comparing lesbians or gays and bisexuals to heterosexuals. Results indicated that the explanatory variables accounted for most of the variance in this relationship, with both risk-enhancing and risk-reducing pathways. Mental health, life dissatisfaction, alcohol use, exposure to tobacco marketing, and single relationship status were risk enhancers for most LGB participants. Health-care access and income level were risk enhancers for bisexual participants only. Neither emotional support nor attitudes and knowledge about tobacco use helped explain the relationship between sexual orientation and smoking. These findings have significant implications for tobacco prevention and control efforts in this high-risk population.