This study explored the reported processes, conditions, and consequences of lesbian and heterosexual female smoking and relapse to understand the reasons for elevated lesbian smoking rates. Using grounded theory techniques, we conducted semistructured, face-to-face interviews with an ethnically diverse sample of 35 lesbian and 35 heterosexual female participants in Northern California. We found minority stress/sexual stigma to be an additional, unique cause of negative emotions and stress reported by 75% of lesbian participants, leading to smoking and relapse. Implications for smoking cessation programs tailored to lesbians are discussed.