This paper explores the question of whether all or most explanations in biology are, or ideally should be, ‘mechanistic’. I begin by providing an account of mechanistic explanation, making use of the interventionist ideas about causation I have developed elsewhere. This account emphasizes the way in which mechanistic explanations, at least in the biological sciences, integrate difference-making and spatio-temporal information, and exhibit what I call fine-tunedness of organization. I also emphasize the role played by modularity conditions in mechanistic explanation. I will then argue, in agreement with John Dupré, that, given this account, it is plausible that many biological systems require explanations that are relatively non-mechanical or depart from expectations one associates with the behaviour of machines.