Though non-indigenous strains of rubber-yielding trees were first introduced into South and South-East Asia in 1876–77, it was not until after 1900 that this crop was widely planted for commercial purposes. Thereafter development proceeded at a pace outstanding in tropical agriculture. During the span of some two decades a major raw material industry was established, totalling 4,250,000 acres by 1922 and situated principally in Malaya (2,260,000 acres), the Netherlands East Indies (1,229,000 acres) and Ceylon (443,000 acres). The main features of this process, such as the company flotation boom of 1909–10, have long been known but much of the work to date has been of a descriptive, very general, nature. The object of this paper is to examine the course of investment in a more detailed and analytical manner. To do the subject full justice, equal attention should be devoted to the activities of European and Asian rubber growers, but the sources of comparable quantitative evidence for the period under review are much more detailed for the former group.