The writing of science history may itself be regarded as a scientific enterprise, involving evidence, hypotheses, theories, and models. I wish here to investigate several historiographic models and their variants. While these undoubtedly do not exhaust the store available to imaginative historians of science, they nonetheless represent, I believe, those that have played the significant roles in the development of the discipline, either as models that have long functioned in historical writing or as models more recently proposed in metahistorical works.