Breast cancer is the most common cancer among women in the United States with over 60% of cases diagnosed as early stage disease. For those women without prohibiting clinical or cosmetic concerns, a choice between breast-conserving surgery and mastectomy can be made. Either choice confers equivalent survival. The decision-making process also involves consideration of recurrence risk as well as management of the unaffected, contralateral breast for both future surveillance and risk reduction. In recent years, increasing rates of mastectomy with contralateral prophylactic mastectomy have been reported among women with unilateral, early stage breast cancer. If eligible for a choice among surgical options, a woman’s decision becomes one of personal preference. The decision-making process is complex and involves consideration of potential benefits and harms with each option. The purpose of this dissertation was to: 1) analyze the psychometric properties of the Anxiety Subscale of the Depression Anxiety Stress Scale, 2) critically review Decisional Conflict Scales and 3) prospectively identify demographic, clinical, cognitive and affective factors influencing a woman’s decision to choose either breast conserving surgery or mastectomy with contralateral prophylactic mastectomy and to identify self-reported sources of information in the surgical decision-making process. Three manuscripts make up the dissertation. A secondary data analysis was conducted to test the psychometric properties of the Anxiety Subscale of the Depression Anxiety Stress Scale (DASS). The results of this analysis supported the reliability and validity of the DASS anxiety subscale. A critical review of decisional conflict measures for use with early stage breast cancer patients making surgical treatment decisions was conducted. The results of this review supported the use of Decisional Conflict Scales from a clinical and research perspective. Existing Decisional Conflict Scales show moderate to acceptable reliability. The first two manuscripts provided background and support for the use of scales included in the research study described in the third manuscript. This study was a prospective, exploratory, cross-sectional, mixed-methods study describing factors influencing preference for surgical choice among women with early stage breast cancer. A sample of 78 participants enrolled in the study, 47 who chose breast conserving surgery and 31 who chose mastectomy with contralateral prophylactic mastectomy. Differences were tested between the groups. Women who chose mastectomy with contralateral prophylactic mastectomy were younger, more likely to work full or part-time, had larger tumors and participated in preoperative genetic counselling. Women who chose breast conserving surgery were more likely to have participated in preoperative breast magnetic resonance imaging. Overall, women choosing either surgery were not experiencing severe levels of distress, depression, anxiety or stress although there were individual variations. Women choosing mastectomy with contralateral prophylactic mastectomy were more anxious and had more frequent intrusive thoughts about the diagnosis. They also had less decisional conflict as compared to women choosing breast conserving surgery. Information sources were similar but the most influential information source differed among the two groups. In both groups, intention for surgical choice was matched by the final decision. There are many factors influencing surgical choice among women with early stage breast cancer. Previous work has focused on clinical, demographic and diagnostic processes influencing the decision. With this study, evidence regarding the influence of cognitive and affective factors is described.