This study examined the effects of yoga on quality of life (QOL) and psychosocial outcomes in women with breast cancer undergoing radiotherapy. Sixty-one women were randomly assigned to either a yoga or a wait-list group. Yoga classes were taught biweekly during the 6 weeks of radiotherapy. Participants completed measures of QOL, fatigue, benefit finding (finding meaning in the cancer experience), intrusive thoughts, sleep disturbances, depressive symptoms, and anxiety before radiotherapy and then again 1 week, 1 month, and 3 months after the end of radiotherapy. General linear model analyses revealed that compared to the control group, the yoga group reported significantly better general health perception (p = .005) and physical functioning scores (p = .04) 1 week postradiotherapy; higher levels of intrusive thoughts 1 month postradiotherapy (p = .01); and greater benefit finding 3 months postradiotherapy (p = .01). There were no other group differences in other QOL subscales for fatigue, depression, or sleep scores. Exploratory analyses indicated that intrusive thoughts 1 month after radiotherapy were significantly positively correlated with benefit finding 3 months after radiotherapy (r = .36, p = .011). Our results indicated that the yoga program was associated with statistically and clinically significant improvements in aspects of QOL.