Over 100 years since Marx′s value theory of labour was first published, the ″transformation problem″ – deriving prices from values and providing a theory of profits as arising from surplus value – continues to present a fascinating challenge to economists of all shades of intellectual persuasion. However, while mainstream economists have by and large come to dismiss the transformation problem as a trivial technical exercise, the issue has recently received renewed attention in heterodox economic theory. This chapter provides a broad historical overview of the transformation problem, highlighting the main ontological similarities and di erences of its proposed solutions. Specifically, I discuss (i) how the interpretation of transformation problem has changed over time, (ii) why it was put to rest in mainstream economics and (iii) to what extent it has regained prominence in contemporary Marxian economics.