Perceived social support has shown to be key to adjustment along the cancer trajectory, but results remain contradictory about the disclosure of the experience of the illness (social sharing) and may reflect the importance of patients characteristics. The authors explored the associations between social sharing, perceived social support, and emotional adjustment in nonmetastatic breast cancer patients and how alexithymia may impact these associations. One hundred and thirteen women with breast cancer from a cancer care center in Villejuif (France) were assessed after breast surgery. Participants completed measures of depression, negative affect, and alexithymia together with a self-description of social sharing of their disease experience and perceived social support. Higher depression and negative affect were related to a high level of emotional sharing, a low satisfaction with confidant's reactions, and a high perceived negative support. In comparison with low-alexithymia patients, those with high alexithymia showed positive associations between negative emotional outcomes and (1) negative social support and (2) emotional sharing. These results suggest that the relationships between social sharing/support and emotional outcomes depend also on individual characteristics, such as alexithymia. Assessing perceived social support and alexithymia in cancer patients is useful to identify who might benefit from social sharing. Interventions could focus on helping the social network and environment to adjust to the socioemotional characteristics of breast cancer patients along the cancer trajectory.