This report focuses on the trends of adolescent and youth well-being in Tanzania, identifying how and why well-being has or has not changed over time. The report conceptualizes well-being holistically. Well-being can be defined as one's ability and opportunity to learn, make decisions, live a healthy life (physically and mentally), be well-nourished, express agency, have peace of mind, and ultimately be economically empowered. Well-being can be accumulated over time and is a composite of multiple aspects that affect the life one lives and the quality of that life. In many ways, how to live a good life and whether one is living this good life has been a key question asked across countries, and there are multiple frameworks that have been used to measure well-being. For the purposes of this study, six domains of well-being are recognized: (1) education and learning, (2) bodily integrity, (3) health, (4) psychological well-being (peace), (5) voice and agency, and (6) economic empowerment and skills. These domains are interconnected, and, also considered is the idea of peace of mind, without which, there is no wellness.