The four tenets of the Strong Program are compatible with a scientific realism founded on an externalist epistemology. Such an epistemology allows that appropriate norms of rationality may differ from time to time, and from community to community, and thereby enables the realist to embrace strong forms of the ‘symmetry principle’. It also suggests a fruitful collaborative research program in externalist social epistemology. Some of what the Edinburgh School says about truth can also be accepted. But the realist should reject the School's argument for the claim that there is no distinction between being rational and being locally accepted as rational, which seems to rest on a kind of epistemological internalism.