This study monitored women (N = 76) with breast cancer from diagnosis through 1 year, and tested constructs from subjective expected utility theory with regard to their ability to predict patients' choice of surgical treatment as well as psychological distress and well-being over time. Women's positive expectancies for the consequences of treatment generally were maintained in favorable perceptions of outcome in several realms (i.e., physician agreement, likelihood of cancer cure or recurrence, self-evaluation, likelihood of additional treatment, partner support for option, attractiveness to partner). Assessed before the surgical decision-making appointment, women's expectancies for consequences of the treatment options, along with age, correctly classified 94% of the sample with regard to election of mastectomy versus breast-conserving procedures. Calculated from the point of decision making to 3 months later, expectancy disconfirmations and value discrepancies concerning particular treatment consequences predicted psychological adjustment 3 months and 1 year after diagnosis.