Preliminary analyses of the first data from the BOUNCE H2020 project (https://www.bounce-project.eu/) have revealed notable findings. Responses to the extensive questionnaires concerning mental health and quality of life have been obtained from 660 women before undergoing treatment for breast cancer in four European nations (Finland, Portugal, Israel, and Portugal). After controlling for basic sociodemographic variables (e.g., age, marital status, education), 25% and 60% of the variance in global quality of life and overall mental health, respectively, was accounted for by psychological variables. Self-efficacy for dealing with the challenges related to breast cancer, optimism, current affect, emotion regulation strategies, and trait resilience were the stronger correlates of the above-mentioned outcomes. Women’s beliefs about their personal abilities to deal with adversity, emotions and the ability to effectively regulate these, are the psychological factors more strongly related to subjective well-being soon after a breast cancer diagnosis. The project is currently following up these women through the first year of cancer treatments to identify long term predictors of successful coping.