Objectives Dispositional optimism is viewed as a key personality resource for resiliency and has been linked to adjustment among women with breast cancer. The aim was to examine (a) the psychometric proprieties of Life Orientation Test‐Revised (LOT‐R), (b) the potential independence and co‐occurrence of positive and negative dimensions of future outcome expectancies, (c) the longitudinal invariance of LOT‐R and the temporal stability of dispositional optimism over 2 years following surgery, and (d) the predictive impact of optimism and pessimism on emotional distress among women with breast cancer. Methods Data from a prospective study (n = 750) of women with breast cancer were acquired shortly after surgery, and the women were followed up for 2 years. Assessments of LOT‐R, Hospital Anxiety and Depression Scale, treatment‐related, and demographic variables were subjected to structural equation modeling analysis. Results A bidimensional and temporarily invariant structure of LOT‐R displayed acceptable fit indices. Three profiles of future expectancies consisting of optimists, pessimists, and ambiguous were identified. Temporal stability in optimism and pessimism over 2 years was established. Women with higher education displayed higher degrees of pessimism. Baseline dispositional optimism inversely predicted emotional distress at 2 years. Conclusions The LOT‐R should be approached as a bidimensional measure. Co‐occurrence of optimism and pessimism may indicate a cautious defensive coping effort in women with breast cancer. The importance of systematic efforts to enhance optimism as well as the capacity to acknowledge both positive and negative future expectancies is emphasized.Copyright © 2015 John Wiley & Sons, Ltd.