Diaconal science, diaconal ethics and diaconal theology - this is the basic thesis of this book - are to be understood as a form of public theology, as diaconia is both a place and an actor in public theology. Public theology is the critical reflection of the workings and effects of Christianity on society. At the same time, it participates in the public discourse on human dignity and image of man, justice and solidarity, in short: in the discussion about the society in which we want to live. If it is true that the church is essentially diakonia, it is immediately obvious that diaconal theology is to be practiced as a public theology. At the same time it shows that the problems of public theology - for example the question of the translatability of Christian convictions into the secular language of a pluralistic society and the question of the relationship between church, public and civil society - are particularly urgent in diakonia today. This is shown by the discussions about the catchphrase of diaconal identity. Diaconal theology as a form of public theology is a search movement and is still largely an unredeemed desideratum. This book would like to participate in this search movement. It strikes an arc from basic questions and fundamentals of diaconal science to practical individual topics with a focus on questions of care and care for the elderly.