In 2015, all the member states of the United Nations signed up to the 2030 Agenda for Sustainable Development and its 17 Sustainable Development Goals (SDGs) [1]. SDG 3 aims to “ensure healthy lives and promote well-being for all at all ages.” Central to this goal are the concepts of health and well-being. This is at least as true for adolescents (10–19 years) as for any other age group. The United Nations Secretary General’s Global Strategy for Women’s, Children’s and Adolescents’ Health (2016–2030), which aims to “ensure health and well-being for every woman, child and adolescent” within the context of the SDGs, recognizes that adolescents will be central to the overall success of the strategy [2]. Similarly, the World Health Organization (WHO)–United Nations International Children’s Fund–Lancet Commission calls for children (defined as <18 years of age) to be at the center of the SDGs [3]. A recent call was also made for Universal Health Coverage to take a comprehensive approach to addressing the health and well-being needs of adolescents [4]. Adolescent well-being is a personal and societal good in its own right, and at the same time, adolescence is a critical period of the life course when many of the factors that contribute to lifelong well-being are, or are not, acquired or solidified. The direct and indirect effects on adolescents’ well-being of the coronavirus disease 2019 pandemic and the responses to it have reinforced the importance of systems being in place to support the well-being of adolescents. But what is adolescent well-being? And how do adolescent well-being and adolescent health relate to each other? As a contribution to answering these questions, the Partnership for Maternal, Newborn & Child Health and the WHO are leading an initiative of the United Nations H6+ Technical Working Group on Adolescent Health and Well-Being to develop a consensus framework for defining, programming, and measuring adolescent well-being [5]. This framework adds to recent work to develop a Nurturing Care Framework for early child development [6]. It is also part of a broader program of work that includes a multistakeholder Call to Action to prioritize adolescent well-being [7], building momentum for a 2022 “Global Summit on Adolescents,” which will review progress and aim to increase political and financial investments for this population group [8]. Many descriptions of well-being have been developed [9]. Two conceptual approaches dominate discussions: subjective and objective well-being. Subjective constructs emphasize personal experiences and individual fulfillment, which include eudaemonic well-being (e.g., finding meaning in life and experiencing a sense of personal growth), hedonic well-being (e.g., feeling happy and being satisfied with one’s own life), as well as others (e.g., optimism) [10,11]. In contrast, objective approaches define well-being in terms of quality of life indicators such as material resources (e.g., income, food, and housing) and social attributes (education, health, political voice, social networks, and connections) [12]. Such objective indicators commonly reflect capabilities, which include both an individual’s functioning and the opportunities provided in a given environment, as argued by Sen [13]. “Relational well-being” emphasizes that an individual’s well-being is heavily influenced by their relationships, with well-being seen as emerging “...through the dynamic interplay of personal, societal, and environmental structures and processes…” [14]. Indicators to measure adolescent well-being reflect these two concepts to differing degrees. Measures of subjective well-being apply indicators such as the subjective well-being measure used in the Gallup World Poll [15] and psychological need satisfaction and frustration scales [16], whereas measures of objective well-being use indicators such as the Global Youth Development Index [17], positive youth development indicators [18], or developmental assets scores [19]. Definition and Framework Based on a scoping of the literature and consultations across the UN H6+ Technical Working Group, youth networks, and adolescent-serving organizations, we propose a short and an expanded definition of adolescent well-being (Box 1 ). We also propose five interconnected domains for adolescent well-being and the requirements for adolescents to achieve well-being within each of these domains (Table 1 ). The five domains encompass both subjective and objective constructs and include health as one of the five domains. The domains are also underpinned by gender, equity, and rights considerations. An individual’s degree of independence to access opportunities that foster their own well-being will vary across the decade of adolescence. Although important at all ages, adolescent well-being may, therefore, require greater adult support at younger ages. Box 1 Definitions Proposed definition of adolescent well-being. Adolescents thrive and are able to achieve their full potential. Expanded definition. Adolescents have the support, confidence, and resources to thrive in contexts of secure and healthy relationships, realizing their full potential and rights. Table 1 The five domains of adolescent well-being that underpin the adolescent well-being framework No. Domain Subdomains Requirements include Type of well-being 1. Good health and optimum nutrition • Physical health and capacities. • Mental health and capacities. • Optimal nutritional status and diet • Information, care, and services: access to valid and relevant information and affordable age-appropriate, high-quality, welcoming health services, care, and support, including for self-care. • Healthy environment: such as safe water supply, hygiene, sanitation and without undue danger of injury in the home, safe roads, management of toxic substances in the home and community, access to safe green spaces, and no air pollution. Skills to navigate the environment safely. • Physical activity: Has access to opportunities for adequate physical activity. • Diet: Has access to local, culturally acceptable, adequate, diversified, balanced, and healthy diet commensurate to the individual's characteristics and requirements, to protect from all forms of malnutrition PhysicalNutritionalEmotionalSociocultural 2. Connectedness, positive values, and contribution to society • Connectedness: Is part of positive social and cultural networks and has positive, meaningful relationships with others, including family, peers, and, where relevant, teachers and employers. • Valued and respected by others and accepted as part of the community. • Attitudes: Responsible, caring, and has respect for others. Has a sense of ethics, integrity, and morality. • Interpersonal skills: Empathy, friendship skills, and sensitivity. • Activity: Socially, culturally, and civically active. • Change and development: Equipped to contribute to change and development in their own lives and/or in their communities. • Connectedness: Has access to opportunities to become part of positive social and cultural networks and to develop positive, meaningful relationships with others, including family, peers, and, where relevant, teachers and employers. • Valued: Has opportunities to be involved in decision-making and having their opinions taken seriously, with increasing space to influence and engage with their environment commensurate with their evolving capacities and stage of development. • Attitudes: Has access to opportunities to develop personal responsibility, caring, and respect for others and to develop a sense of ethics, integrity and morality. • Interpersonal skills: Has access to opportunities to develop empathy, friendship skills, and sensitivity. • Activity: Has access to opportunities to be socially, culturally, and civically active that are appropriate to their evolving capacities and stage of development. • Change and development: Has access to opportunities to develop the skills to be equipped to contribute to change and development in their own lives and/or in their communities. EmotionalSociocultural 3. Safety and a supportive environment • Safety: Emotional and physical safety. • Material conditions in the physical environment are met. • Equity: Treated fairly and have an equal chance in life. • Equality: Equal distribution of power, resources, rights, and opportunities for all. • Nondiscrimination. • Privacy. • Responsive: Enriching the opportunities available to the adolescent. • Safety: Protection from all forms of violence and from exploitative commercial interests in families, communities, among peers and in schools, and the social and virtual environment. • Material conditions: The adolescent's rights to food and nutrition, water, housing, heating, clothing, and physical security are met. • Equity: There is a supportive legal framework and policies and equitable access to valid and relevant information, products, and high-quality services. • Equality: Positive social norms, including gender norms, to ensure equal rights and opportunities for all adolescents. • Nondiscrimination: Free to practice personal, cultural, and spiritual beliefs and to express their identity in a nondiscriminatory environment and have the liberty to access objective, factual information, and services without being exposed to judgmental attitudes. • Privacy: Their personal information, views, interpretations, fears, and decisions, including those stored online, are not shared or disclosed without the adolescent's permission. • Responsive: Has access to a wide range of safe and stimulating opportunities for leisure or personal development. PhysicalEmotionalSociocultural 4. Learning, competence, education, skills, and employability • Learning: Has the commitment to, and motivation for, continual learning. • Education. • Resources, life skills, and competencies: Has the necessary cognitive, social, creative, and emotional resources, skills (life/decision-making) and competencies to thrive, including knowing their rights and how to claim them, and how to plan and make choices. • Skills: Acquisition of technical, vocational, business, and creative skills to be able to take advantage of current or future economic, cultural, and social opportunities. • Employability. • Confidence that they can do things well. • Learning: Receives support to develop the commitment to, and motivation for, continual learning. • Education: Has access to formal education until age 16, and opportunities for learning through formal or nonformal education or training beyond. • Resources, life skills, and competencies: Has opportunities to develop the resources, skills (life/decision-making), and competencies to thrive. • Skills: Has opportunities to develop relevant technical, vocational, business, and creative skills. • Employability: Is given the opportunity to participate in nonexploitative and sustainable livelihoods and/or entrepreneurship appropriate for their age and stage of development. • Confidence: Is given the necessary encouragement and opportunities to develop self-confidence and is empowered to feel that they can do things well. EmotionalCognitive 5. Agency and resilience • Agency: Has self-esteem, a sense of agency and of being empowered to make meaningful choices and to influence their social, political, and material environment and has the capacity for self-expression and self-direction appropriate to their evolving capacities and stage of development. • Identity: Feels comfortable in their own self and with their identity(s), including their physical, cultural, social, sexual, and gender identity. • Purpose: Has a sense of purpose, desire to succeed, and optimism about the future. • Resilience: Equipped to handle adversities both now and in the future, in a way that is appropriate to their evolving capacities and stage of development. • Fulfilment: Feels that they are fulfilling their potential now and that they will be able to do so in the future. • Agency: Has opportunities to develop self-esteem, a sense of agency, the ability to make meaningful choices and to influence their social, political and material environment, for self-expression and self-direction. • Identity: Has the safe space to develop clarity and comfort in their own self and their identity(s), including their physical, cultural, social, sexual, and gender identity. • Purpose: Has opportunities to develop a sense of purpose, desire to succeed, and optimism about the future. • Resilience: Has opportunities to develop the ability to handle adversities both now and in the future, in a way that is appropriate to their evolving capacities and stage of development. • Fulfilment: Has opportunities to fulfill their potential now and to be able to do so in the future. EmotionalCognitive The examples that are given in the subdomains and the requirements to achieve these are illustrative and not exhaustive. Implications for Policy and Practice The definition of adolescent well-being and its five domains applies everywhere and is relevant for all adolescents, including males and females, wealthy and poor, and the able-bodied and those with chronic disability, for example. They also emphasize the multidimensional nature of well-being. Therefore, programming to improve adolescent well-being will require a multisectoral approach, and the measurement of adolescent well-being will require multidimensional indicators that encompass all five domains and include both subjective and objective measures. It is for this reason that in addition to working toward a consensus set of health indicators, the multiagency Global Action for Measurement of Adolescent Health initiative led by WHO involves assessing indicators of adolescent well-being, with a view to agreeing on a core set of well-being indicators [20]. Conclusion Maintaining and improving the well-being of its citizens is the fundamental duty of all governments, supported by the United Nations, civil society organizations, private sector, families and communities, adolescents, among many others. This requires a clear definition and measurable indicators. Given the multidimensional nature of well-being, spanning five domains, it will be essential that multiple sectors unite behind the common objective of improving well-being, using a common set of definitions, concepts, and indicators. Here, focusing on adolescents, we have proposed the first two of these requirements—a clear definition and description of five domains that underpin a conceptual framework for adolescent well-being, whereas work continues on the development of the common set of indicators and the policy and programming implications of this framework.