I defend the epistemic account of scientific progress as the accumulation of scientific knowledge by showing that it can account for many cases of scientific progress that are not accounted for by the noetic and functional accounts. There are many instances of modest contributions to progress through the addition of new scientific knowledge that does not bring with it new understanding or new exemplary practices. I show that such cases are to be found in the history of biology and of astronomy. Progress can be made also by knowing that some novel phenomenon, such as X?rays, exists, even when that knowledge does not include new understanding or new methods and practices.