Few studies have assessed quality of life (QOL) of women diagnosed with breast cancer within the first few weeks of their initial diagnosis. We describe QOL among 950 women recently diagnosed with invasive breast cancer. Starting in January 2006, we invited women aged > or =21 years who were diagnosed with first primary invasive breast cancer within Kaiser Permanente Northern California (KPNC) to enroll in the Pathways Study, a prospective study of breast cancer survivorship. QOL was measured using the Functional Assessment of Cancer Therapy-Breast Cancer (FACT-B), along with sociodemographic and social support information. Clinical characteristics were obtained from the KPNC cancer registry and electronic medical record. We used multivariable linear regression models to identify factors associated with QOL scores calculated from the FACT-B. The mean age +/- SD of the sample was 59.6 years (+/-11.9 years), and the mean time +/-SD from diagnosis until interview was 8.0 weeks (+/-3.2 weeks). Younger age at diagnosis was associated with lower scores in all QOL domains (P < 0.01), and later stage at diagnosis was associated with lower scores in all domains (P < 0.05) except for social well-being. Higher levels of social support were associated with higher QOL except for physical well-being (P < 0.05). These associations were stronger within 2 months of breast cancer diagnosis. Quality of life as influenced by a diagnosis of breast cancer is an important factor in cancer survivorship. Age, stage at diagnosis, and social support are key factors in this important variable.