Introduction

The goal of global gender equality is articulated in the fifth Sustainable Development Goal (SDG 5). This objective signifies the global community's recognition, for the first time, of the central role that gender equality plays in sustainable development. However, the importance of gender equality in the Sustainable Development Goals goes beyond SDG 5. Issues of equality, and specifically gender equality, are interwoven throughout the SDGs and are central to both SDG targets and their related efforts that range in scope from the individual through macro-national and global political institutions.

Independent of the SDGs, adolescent health and well-being have recently emerged as national and global priorities (Patton et al, 2016). For some, the increased importance of adolescents and youth reflects the impressive child survival successes under the MDGs (Bhutta et al, 2019). It is also an acknowledgement that this segment of the population represents a political and social force; there is a critical need to support young people's growth and development if they are to participate in national growth and development. The SDG era (2015– 30) provides an opportunity to highlight the needs of adolescents worldwide, by putting a growing body of longitudinal evidence into practice in the evaluation of SDG-relevant programmes, tracking the achievement of SDG targets among adolescents, and ultimately developing policies that ensure no one, especially this next generation of national and global leaders, is left behind. In order to ensure just and sustainable global development, policy makers must understand the experiences and concerns of adolescents around the world. However, despite their critical role in global development, adolescents are essentially absent from most SDG indicators (Guglielmi and Jones, 2019).

The work of the Global Early Adolescent Study (GEAS) is especially compelling within the SDG context because, until recently, little was known about the first five years of adolescence. Most research began at age 15 and approached young adolescents with assumptions about their experiences, rather than evidence. We know now that early adolescence is not only a time of rapid pubertal development but also of neurological development that impacts social and cognitive functioning (Dahl et al, 2018).

These developmental changes take place within the context of dramatic shifts in social expectations, and in adolescents’ relationships with family, friends and romantic partners as they mature (Cohen et al, 2003).