This study critically analyses the role of Happiness among the Portuguese elderly. The term is understood as a grouping of variables including Subjective Well-being, defined by satisfaction with life, positive and negative affects, flourishing, optimism and pessimism, positive and negative emotions, meaning of life, religiosity, Spirituality, and mindfulness. The qualities of Happiness are explored as they contribute to successful ageing and higher levels of Happiness in the elderly. We conducted a correlational study of 329 participants, aged 55 to 98 years. We used several questionnaires to gather data as a socio-demographic questionnaire, Satisfaction with Life Scale (SWLS), Positive and Negative Affect (PANAS), Mindful Attention Awareness Scale (MAAS), Flourishing Scale (FS), Positivity test (PST), Mental Health Inventory-5 (MHI-5) Life Extended Orientation Test (LOT) and Meaning Life Questionnaire (MLQ). Results indicated the meaning of life, mindfulness attention, positive emotions and optimism are important factors for ageing well. On the contrary, gender, marital status, religiosity, and income are not predominant factors of Subjective Well-being in ageing. This study found six significant predictors of flourishing: satisfaction with life, positive or negative affects, optimism, positive and negative emotions, meaning of life, and mindfulness attention.