Engaging with youth is no longer an option: the "Millennials" are a growing constituency that pushes an increasingly coherent agenda. The newly adopted Sustainable Development Goals represent an unprecedented opportunity: they acknowledge youth, address issues that are of particular concern to young people, and invite updated approaches to youth engagement. How might the energy, creativity, and skills of "Millennials" be leveraged to co-create positive change in policy; advocacy and campaigning; programming, monitoring, and accountability; communication and research, etc.?