['Breast cancer survivors who have completed surgery and adjuvant treatment have distinct social support needs that may relate to emotional health. There is little research on both levels of social support following treatment and the association between social support and emotional well-being over time following breast cancer diagnosis and treatment. The aims of this study were to assess (1) the direction and magnitude of change in social support quality and quantity and (2) the degree to which change in quality and quantity of social support predicted change in emotional well-being over time following completion of breast cancer treatment.', 'A sample of 157 female breast cancer survivors (M', 'Social support quantity significantly decreased over 1\xa0year, while social support quality remained stable. Based on change score analyses, a decrease in social support quality was a significant predictor of increases in depression, stress, and negative affect, explaining an extra 4 to 6% of variance in the emotional well-being outcomes compared with social support quantity.'] Do changes in social support predict emotional well-being in breast cancer survivors?