My article on the state-of-the-art in Esperanto linguistics has been published in Language Problems and Language Planning 41:2 (2017).
Esperanto is an unusual language in many ways. First, it was originally created artificially, in a highly multilingual environment. Secondly, it was designed with the express purpose of becoming a language of interlingual communication, a language easy to learn for people from the widest range of linguistic backgrounds. Although it never became a universal lingua franca, Esperanto now has up to 2 million users and a sizeable number of native speakers. Yet even for such native speakers, Esperanto is never their only language. Its use is limited to certain domains, and for the overwhelming majority of its speakers, including native ones, Esperanto is not their dominant language. These facts may make Esperanto and Esperanto speakers useful in tests of the robustness of generalizations about linguistic typology, Universal Grammar, first and second language acquisition, language contact and creolization, variation and change. This article provides an overview of work that has been done to date on these topics.