['Physical activity is beneficial for cancer survivors, but exercise participation is low in this population. It is therefore important to understand the psychological factors underlying exercise uptake so that more effective interventions can be developed. Social-cognitive theory constructs such as outcome expectancies predict exercise behavior, but self-report measures have several limitations. We examined the associations between implicit (automatic) cognitions and exercise behavior and self-efficacy in endometrial cancer survivors.', 'This was a longitudinal study to examine predictors of exercise behavior in female endometrial cancer survivors who all received an exercise intervention. Participants (N = 100, mean age of 57.0) completed questionnaires to assess self-report exercise-related measures (outcome expectancy and attitudes about and identification with exercise) and reaction time (RT) tasks to assess implicit exercise cognitions (expectancy accessibility, implicit attitudes about exercise, and implicit self-identification with exercise) at baseline and at 2, 4, and 6 months at follow-up. Exercise behavior was measured using accelerometers and self-report. Data were analyzed using linear mixed models.', 'Expectancy accessibility was associated with exercise duration independent of the corresponding self-report measure. Exercise implicit attitudes and self-identification were prospectively associated with exercise self-efficacy only after adjustment for the corresponding self-report measures and baseline self-efficacy. Self-report measures were also associated with study outcomes.'] Are self-reported and automatic cognitions associated with exercise behavior in cancer survivors?