Here we try to characterize the fringe of science as opposed to the mainstream. We want to do this in order to provide some theory of the difference that can be used by policy-makers and other decision-makers but without violating the principles of what has been called ‘Wave Two of Science Studies’. Therefore our demarcation criteria rest on differences in the forms of life of the two activities rather than questions of rationality or rightness; we try to show the ways in which the fringe differs from the mainstream in terms of the way they think about and practice the institution of science. Along the way we provide descriptions of fringe institutions and sciences and their outlets. We concentrate mostly on physics.