Ludwig Lachmann is a central but underappreciated figure within the Austrian school of economics. Although his understanding of institutions, his appreciation of the heterogeneity of capital, his emphasis on subjectivity, and his focus on the dynamism and uncertainty of the real world have become dominant positions amongst Austrian economists, he is still viewed as something of an outsider. As such, the contributions of Lachmann's economics are arguably misunderstood. This Element attempts to tease out and discuss the critical contributions of Lachmann's economics. Arguably, one way in which to understand Lachmann's economics is by seeing it as unified in considering, in various ways, a single conceptual 'problem' – the apparent tension between the dynamic nature of social reality and the intelligible nature of the social world. Approaching Lachmann with this theme in mind allows us to put things together more coherently than other exegetical strategies.