The problem of the proliferation of aid donors and channels continues to worsen. It undermines the value of aid. We contribute to the existing literature by (a) categorising the apparent adverse effects of proliferation; (b) producing a reliable and fair indicator of the extent to which the main bilateral donors proliferate or concentrate their aid; © explaining why some donors proliferate more than others; (d) constructing a reliable measure of the extent to which recipients suffer from the problem of fragmentation in the sourcing of their aid; and (e) demonstrating that the worst proliferators among the aid donors are especially likely to be suppliers of aid to recipients suffering most from fragmentation. There are significant implications for aid policy.