The goal of this introductory chapter is to show how debates about scientific explanation in the philosophy of biology and in the philosophy of history can be conjoined to stimulate and enrich each other. We draw attention to two major points of contact: first, it seems as if historical explanations are not restricted to the historical science, but can be found for instance in the biological science as well (most notably in evolutionary biology). This raises the question of what it is that makes a scientific explanation “historical”. Second, in philosophy of biology and in philosophy of history we recently find an emphasis on the role of mechanisms and mechanistic explanation in both sciences. But are there really such things as historical or social mechanistic explanations, and how do they relate to biological mechanistic explanations? In this paper we introduce different answers to these questions and argue that they enable and demand a joint and mutually stimulated discussion, by philosophers of history and by philosophers of biology.