Boltzmann’s Bildtheorie, which asserts that scientific theories are ‘mental pictures’ having at best a partial similarity to reality, was a core element of his philosophy of science. The aim of this article is to draw attention to a neglected aspect of it, namely its significance for the issue of scientific explanation and understanding, regarded by Boltzmann as central goals of science. I argue that, in addition to being an epistemological view of the interpretation of scientific theories Boltzmann’s Bildtheorie has implications for the nature of scientific understanding. This aspect has as yet been ignored because discussion of the Bildtheorie has been restricted to the realism-instrumentalism debate. To elucidate my analysis of Boltzmann’s Bildtheorie concrete examples are presented, and the pragmatist and Darwinist roots of Boltzmann’s view are discussed.