Educational publishing underpinned the Australian publishing industry's profitability and development throughout the twentieth century. While largely invisible to the general trade market, educational publishing comprised up to a third of the $2 billion Australian publishing market. Investment in educational publishing late in the 19th and early in the 20th century and again in the 1950s and 1960s led to increased general publishing by local and international publishers. For instance, Angus & Robertson achieved its pre-eminent position in Australian publishing in the middle of the 20th century supported by the profits of its strong school and university textbook lists and the famous editor Beatrice Davis was initially lured to the firm to work on textbooks before she established herself as a major gatekeeper for the publication of Australian literature. In the latter half of the 20th century, many publishers underwrote their trade publishing with profits from educational lists, which included major reading programs from Pearson, Mimosa, Macmillan and other publishers (a significant number of which were exported to other markets) and complex projects in subject areas such as mathematics and science. Globally, however, publishing companies were expanding in size, yet consolidating their output. As of 2011, four publishers - Pearson, McGraw-Hill, Cengage, and Wiley - dominated English language (and Australian) educational publishing. Only one, Pearson, continues to publish in the trade market. As well, the first decade of the 21st century saw many curriculum areas being serviced with digital materials with the educational publishing sector struggling to maintain its traditional role as supplier of educational materials. Trade publishers are now totally reliant on their own products, with no underwriting of risk from educational products. What impact these developments will have on Australian publishing as it confronts the digital challenge has yet to be determined.