Servant leadership focuses on the well-being of those being served, helping them become healthier, wiser, freer, and more autonomous. The emphasis on becoming implies inner development. This chapter links servant leadership with a recent initiative, the Inner Development Goals (IDGs). This chapter draws heavily on developmental psychology and, more specifically, adult development to emphasize the need for developing more mature versions of ourselves to meet external challenges such as the UN Sustainable Development Goals (SDGs). Developmental psychology uses a maturity model that maps out how the ego, or sense of self, goes from developing into a mature and healthy self to transitioning into a more transcendent or selfless way of functioning in the world. This chapter lays out the parallels between servant leadership and adult development, using the IDG project as an example, and provides a rich set of perspectives that can help illuminate certain aspects of servant leadership and how it can be developed.