Many commentators have expressed the worry that the actual content of science is neglected in much of the recent work in the history of science.  Conflicting attitudes on this issue have produced some unproductive and misguided divisions in our field.  I wish to advance a thesis that is at once controversial and obvious: there is a distinct set of objectives in the history of science that cannot be met if we do not engage with scientific knowledge itself and with the methods used by scientists in pursuit of knowledge. Moreover, such objectives can only be fully met if our engagement with science is critical, based on the historians’ own epistemic judgements that are independent from the current scientists’ judgements. These conclusions are enhanced and enriched when we consider the functions of history in general, and how they may best be served when science is our object of historical study. What I envisage is not a revival of old-style internalism, but the flourishing of a mature discipline of the history of science that takes science seriously both as a socio-cultural phenomenon and as an epistemic practice.