This article responds to Pope Francis’s call in Laudato Si’ for an ecological expansion of mission and seeks to provide it with theological support. This support comes by way of a trinitarian rendition of the missiological concept missio Dei. Drawing from Thomas Aquinas and Bernard Lonergan’s accounts of the trinitarian missions, it articulates a theological ecology (as opposed to an ecological theology), in which the traditional doctrine of God is the controlling motif. Through the missions of the Son and Holy Spirit, God transforms the moral-intellectual-volitional comportment of humanity and recruits them into a shared mission of environmental concern.