Development aid is considered an important instrument in achieving a more sustainable global future. However, the general public perceives aid as rather inefective. This may be because the public knows little about aid and its efects. Evidence for the efects of aid projects may therefore be of particular importance in shaping attitudes. In a survey experiment carried out among the German population (N ≈ 6000), we presented a claim on the efectiveness of an aid project or the same claim plus experimental evidence, qualitative evidence or anecdotal evidence and compared it to a no information control group. Results revealed that the claim increases both belief in the efectiveness of aid as well as support for aid. Among all forms of evidence tested, anecdotal evidence performs best, followed by experimental evidence. Pre-manipulation support for aid partly moderates the efect of the claim, but those who support aid do not react more strongly to the two forms of scientifc evidence (experimental/qualitative).