In this article I think through a particularly problematic problem in the theology of prayer. Problems in the theology of prayer usually have to do with concerns around the relation between divine and human agency in prayer, the effects of prayer (on God, the pray-er, both or none) and difficulties in the practice of prayer itself. When prayer is not the problem, it is often taken to be the solution to all manner of things -- as we shall see below. The particular problem I want to explore in this article, however, is more fundamental than the usual problems in prayer discourse and focuses specifically on the need for a more realistic theory of prayer than one that views prayer as the solution to everything. What I am alluding to has been recently theorised as not only a problem, but a danger: the ever-present danger of prayer going wrong, and so inflicting damage and distress. After a description of the broad shape of the danger argument I turn to the writings on prayer by Karl Barth as representative of the prayer-as-the-solution-to-everything trope and show that the prayer-sections are especially vulnerable to the dangers problem. Then, in the final section of this article, I reach beyond the prayer-sections of the Church Dogmatics to present Barth’s idea of the Schattenseite (‘shadow-side’) of creation as a way of encouraging more disciplined thinking about prayer -- one that is self-critical, alert to and realistic about the dangers of prayer and yet not without hope in the promise of prayer’s remaking. I call this way of thinking about prayer a ‘negative’ theology of prayer.