This session will discuss recent ideas and strategies on the complex topic of obtaining evidence of impact. An underlying aim is for us as a field to work together, rather than in isolation, to define, to determine, and to communicate to funders, policymakers and others in the field impact criteria that are meaningful for informal science institutions. Two institutions will present methods and framework ideas; the third speaker will introduce the idea of an Ecsite special interest group on impact, leading to small group discussions with key points to be shared by all.